> Web developers weren't professional enough to make the web fast.
Don't shit on (other?) developers to make your point. It's revisionism that only serves the purpose of taking more control from users and developers, which just conveniently gives even more power to the stakeholders who most benefit from the structurally unsound game businesses have been playing.
By the same logic, I could say the Google Chrome team (not related to AMP — just a metaphor) isn't professional enough to make a browser that uses less RAM. In reality, the team deals with a myriad of constraints and other priorities, both technical and commercial, that sometimes clash. Rendering speed and security are its major selling points; if both are met, management is satisfied and Google makes billions.
I'm loath to say this, but performance isn't where a lot of websites make money. It's the ads that people click, way too often by mistake. To feed this system, a bootload of tracking scripts, A/B testing scripts, overeager live support widgets...
Google is coyly selling preferred placement in exchange for performance, which may be the only way to get some businesses to care about performance. Developers are cranking out what the business owners are asking for.
Ask yourself why Google did not take aim at the ownership side, why it did not arrange discussions with major media companies etc. to establish performance as a company-wide goal, instead, put the responsibility on developers.
> Before that, people were massively moving to the apps because the web got too slow and unusable on mobile.
Yeah, the thought process to go from seeing the "use our mobile app instead! It's so much better!" banner, closing it and sending my eyes onto the content that I wanted to read takes at least half a second.