My guess is: it's a lot of work, prone to cause bugs, most users don't notice or care, and highly-paid FAANMG programmers could be working on other things. I'v

My guess is: it's a lot of work, prone to cause bugs, most users don't notice or care, and highly-paid FAANMG programmers could be working on other things. I've noticed this effect happen with websites too. Click around on Facebook enough (such as the ads platform) and you might suddenly get a page with an older circa-2010 look.