This I think is a matter of preference and strategy.
When I got my first iPhone, I had to go with third party services because I owned outdated Apple products (and I still do). Google's services work just fine on an iPhone and on Android. While I like iPhone, I can come and go as I please. I've also had a Yahoo account since 1999, and that works on iPhone. So I could readily convert to Yahoo's services on both platforms.
Both Google and Yahoo work cross platform and on older systems. Apple, not so much.
I use Dropbox as well, a service I've had since around 2009 and predating my purchase of an iPhone by three years. I use it to get photos and videos from my phone to my Macs and PCs.
iMessage can be used on Android by using AirServer. It requires a dedicated 24/7 Mac that can use the Messages app but it works. And back in the day I was jailbreaking to get stuff Apple wouldn't allow. For instance, I've had dark mode on my iPhone since early 2013.
For other things, it just doesn't matter. For instance, nothing sensitive is ever sent by text in my household. Everything of that nature is discussed face to face. If someone were to review my iMessages they'd find a lot of grocery lists.
My point is that you can choose. But until Apple actually locks out third party services on their devices, you aren't bound by that choice.