The answer to that question is that they're either lazy, ignorant or both. :D
In all seriousness. I can imagine that a lot of developers who work on commercial products are given about 20% of the time and resources needed to make a good product. I don't blame them for doing what it takes to not get fired.
And we only have proprietary software because there's greedy people out there that take advantage of people who don't know better.
With that said. I'm not saying that developers shouldn't get paid for what they do. They absolutely should! And a lot of them do, even when the code is free as in free beer and free speech.
And 100% of the parents needs to stop using big tech. They're parents and they can't do dumb shit and not expect their kids to do the same thing as them.
Helium should be fine. They're, to my understanding, a fork of ungoogled-chromium, and they seem to proxy all calls to Google for you. It shold be a safe enough web browser for 'regular' people who care about their privacy.
I believe it's mainly going to affect the regular users who use regular Google Android, for the simple reason that people who understand this is either power users or developers. The developers is most likely going to a) quit it all together or b) move exclusively to proper alternatives like F-Droid.
For the very reason that I, and power users, is not relying on any Google services, this is not really going to effect us at all.
Me! I have a Fairphone 6 with LineageOS (without any Google services).