I know that this is a controversial take here, but this sideloading crackdown is just fallout from the inevitable disaster that is mixing general purpose computing with high security and reliability requirements.
There's just no way at this time in which a single computing device can run software with high reliability expectations (emergency calls), high security expectations (controlled calling/texting, banking, money transactions) at the same time as random crap from the internet and keep the user safe and secure.
The HN community is far to fixated on their own use cases to properly understand this issue and its implications which can potentially upset a person's entire existence.
If that "disaster" was so "inevitable", it would have happened ages ago.
It's not like it was somehow possible to accidentally sideload apps. You have to first find the correct option from the system settings to enable sideloading, and then approve the specific app source you want to install from.
It is not like how things are/were on Windows. Back in the turn of the millennium, it was easier to catch malware than it was to install useful apps. For former, you only needed to double-click on an email attachment, for the latter, you needed to actively to go look for the website of the app developer, and download it from there.
Android already was pretty much at the sweet spot between security and freedom, what it came to sideloading. What Google should have done was to crack down on the scam apps in Play Store. However, they are not going to do that, since it would cut their profits.
Disasters can hapoen slowly. This one did, in a series of decisions from multiple actors. The main inflection point was allowing third parties develop for phone platforms. Then banks erc. went through a process that ended up forcing the use of a smartphone exclusively for a lot of applications that are sensitive. The same device runs random code downloaded through various means (app stores, preinstalled bloatware installing even more crap on cheap phomes, websites, embedded webviews for ads...). This is now an entrenched status quo spread across multiple actors and unaligned interests.
I always buy this argument....to the extent that the more powerful, dangerous capabilities are still allowed but locked behind some (one time) process that indicates you have a base level of knowledge and understanding. If you want to make it default safe for normies, fine, but let me turn my own device into the dangerous thing it is capable of being.
The version of the your view that we are actually getting is _incredibly_ paternalistic and condescending to the general populace. The kind of society that is capable of protecting everyone from every conceivable harm comes with the kinds of tradeoffs that no one, not even the people who actually need the protection, are going to want.
Sadly, your view isn't less paternalistic in reality. It effectively amounts to telling people who have better things to do than care about their personal IT security to just suck it up. Billions of smartphone users worldwide are in this position.
Look, I'm not saying that this outcome is ideal and I hate the idea of a single, almighty platform gatekeeper. But with the world being what it is right now, draconian device lockdowns of some kind are the best option that is immediately available.