I think the problem is a lack of "engineering culture".

People experience latency but if you “saw like a corporation” you could only see throughput and never latency.

Obviously not with Gmail/Facebook, in that case it's just 100% incentive misalignment.

The others, probably, VCs are incentivized to fund the people who allocate the most resources towards growth and marketing, as long as the app isn't actively on fire investors will actively push you away from allocating resources to make your tech good.