I presume some of these things are due to accessibility, but Amazon's site is near impossible to navigate even with 20/20 vision and all my faculties. I'm not

I presume some of these things are due to accessibility, but Amazon's site is near impossible to navigate even with 20/20 vision and all my faculties. I'm not advocating for familiarity, but for predictability. It's not that interfaces shouldn't change, but that they should be predictable. If you're changing expected behavior (new tabs, tab, etc) you need the interface to reflect that. If there is something 99% of your users are doing in your page, there's a good chance that it's what should pull focus on page load. Nothing works for all cases, but I think those are good guidelines. You're right about memory management - sadly it's also the SPAs that I see download their entire dependency tree onto my system just to show me a few lines of text.