The Apple Ecosystem
How well they work together
In the world of creating Operating Systems, Apple really has only two competitors to speak of and everyone knows that is Microsoft and Google. These companies have different approaches, though. However, in either case, Apple has wider range of hardware and software.
Microsoft does not compete with Apple in the phone market and Google barely competes with them in the desktop/laptop/tablet market. Therefore, Microsoft and Google clients don't have the benefit of being able to seamless move from the phone, to the tablet, to the desktop, to the laptop. Even when you flip on the TV, AppleTV has advantages with access to iTunes on your computer, your photos instantly appearing in the Photos app, you Podcasts showing up, etc.
The Walled Garden
First off, yes Apple makes it very comfortable in their garden. In fact, it is like living on a continent with everything you need. If you want Disney World, it is in there. If you want, a trip to the Safari, it is in there. That being said, they don't let all of their goodies outside of the wall. In other words, if you want to ride the biggest roller coaster in the world, it isn't available outside those walls, if you want the best beaches in the world, it isn't available outside those walls, etc.
That being said, MKBHD makes the point that they don't want you looking outside those walls. Is that really true? Does Apple stop Google from putting Chrome, Google Play, Google Assistant, YouTube, GMAil, etc inside their walls? If I can see how great Google does these things, aren't I more susceptible to being moved to other Google devices? Microsoft has their incredible office suite on MacOS and iOS. Isn't that letting me peak outside the walls when Apple has their own suite of apps? Heck, they allow Adobe Premier and even Windows to run on Macs. As I said, they have an open gate where pretty much anyone can come in, but they don't let all of their goodies out.
Hooks into the Ecosystem
Also, he mentions how, if you want to leave Apple's Ecosystem, your AirPods aren't as useful. Of course, Apple makes hardware that works well together. If you leave, you lose that benefit. You aren't stuck with anything, though. If I wanted to get out of Apple products, I would just sell the stuff on eBay, Amazon, Gazelle, etc. There are many ways to get rid of tech you no longer want.
As an example, I wanted to upgrade my old speakers. However, if I bought new speakers, my old speakers would be rendered obsolete in my home. Does that mean I am stuck with those old speakers until I die? No, it means that I could sell them and use that money toward new stuff. In the case of Apple, that old stuff typically holds its value better than the competition, so you won't take as big of a hit selling an iPad as an Android tablet. Of course, you could get rid of the iPhone and still use your iPad or iPod Touch to control your HomePod and use your AirPods, so if you were someone that bought into the entire ecosystem, chances are you could still use a lot of stuff if you just got rid of an iPhone. The Mac and iPad don't require you to use an iPhone.
He also discusses moving from Apple Music to Spotify because it is "clearly better". Obviously, this is bias because it isn't backed up by facts. JD Power actually did a study in Sept 2016 and Apple Music came in first and Rhapsody came in second for Consumer Satisfaction. Also, moving your entire library over isn't even possible because Spotify doesn't match your music. So much for being "clearly better".
Hooks into the iPhone
You could be missing out?
It is also why you look at how a 5 month iPhone blows away new flagship phones coming out today in many areas:
In other words, these "best DxOMark" or best "DisplayMate" scores are measured within specific criteria and that criteria may be different from person to person. The iPhone X had the highest score ever from DisplayMate, did everyone throw out their Android phones and switch to iOS on that day? No, because even Android owners live in an ecosystem. If they have apps that only work on Android and they need them, they aren't switching to iOS on a whim. It works both ways.
Personal Experience
However, was this a bad thing? I value having music, in a high quality, in multiple places in my home and only Apple affordably fed that market at the time.
When it comes down to it, we all have our choices to make. I am not trapped by Apple products. I have sold much harder things to get rid of on eBay (5 tires for a Jeep, for example) and I am not trapped by the fact that I own a HomePod. I could sell it tomorrow without much of a problem.
Outside of getting rid of actual products, I already own Windows computers (including Windows running on Macs), so I could move to Microsoft without much issue.
I see the ecosystem as a huge reason I stay with Apple and find it to be the thing that separates them from being solely concerned with specs that really don't add as much satisfaction as features like Airdrop, Airplay, Continuity, Messages, etc.
Final Thoughts
To wrap up....I agree that Apple's ecosystem of devices keeps people buying Apple products and services. I believe it is because people make the choice to take advantage of the ecosystem because the ecosystem makes their lives easier in many different ways. No one is "walled in", though. People always have choice and many are choosing to buy Apple products. It is never "too late" to change things up when you can sell the HomePod, Apple Watch or any Apple product tomorrow. The fact that people don't want to lose Apple's unique features is more about choosing to live in the garden rather than being trapped in the garden.