There's a number of factors:

• Ridiculously bloated libraries. Devs don't want to push back against it because being an expert in one is job security, and managers don't want to push back because having a dedicated person for each library gives an excuse to have more headcount.
• Adding something on top of something else is a natural way to accomplish things, and has a performance penalty, and takes legitimate effort to undo. This effort isn't profitable so it's never prioritized.
• Constant reprioritization and reshuffling of priorities means constantly losing the people who know how the system works. The new people add in a new layer to demonstrate they understand the system.
• Nobody uses a fucking profiler. Because it takes time and the only benefit is performance, which is hard to demonstrate profit from. Also a lot of devs have weird hangups where they think their pet topic is better for performance than using a profiler.
• Adware.
• All the major OS vendors have abandoned development in favor of trying to chase mobile/app store/adware money rather than making their development experience make sense, so there's no coherent way to develop a cross-platform app you're stuck with shit like Electron.

Honestly, I think that's a lot of it. Look at the kind of shit we call cross platform now. Electron apps are running javascript in a chrome process as an appliance for god's sake, it's madness. I don't think devs that know better really like any of that, but it's a way to shove out an app that does stuff I think.