All the above are quick hacks that never really did the job properly in the first place. So they're propped up by a creaking pile of frameworks and other support systems that try to mitigate their awfulness, but mostly just add extra awfulness of their own.

Meanwhile backend systems - core server and db infrastructure, user authentication, computing resource allocation, payments, media and content management, privacy, and project build systems - are even more byzantine and non-standardised and more or less have to be retooled from scratch for every project - a huge job which duplicates an incredible amount of work across the entire industry.

As a corollary/reformulation of that sentence you get that what businesses are trying to do in the web is clearly something it wasn't made for. Yet businesses want to free-ride on the web's success, and are ruining it.