There are many things about modern web development that frustrate and annoy people, but my two biggest issues:1) A lot of SPA websites nowadays break my browser's Back button.  I understand that this is "easy" to fix with push state/history APIs, etc.  But it never used to be this way.  Now you have to do all kinds of special stuff just to get the basic functionality of your web browser back.2) SPA apps almost always have to be specially routed at the webserver level to the index.html.  Again, it never used to be this way.  Without any special server-side routing I now have to visit the main page and then follow a series of SPA links to get to the page I want.  I can't just go directly there anymore because most likely the CDN or webserver will return a 404.  Again, it never used to be this way.  Fundamental aspects of the web have been broken.What are some other annoyances?