How is USB-C not common? It's the default for every remotely modern android phone I've seen, all the modern game consoles I've seen (eg, the Switch and PS5 controllers), and many other random electronics use it (I even had a covid tester that was plugged into USB-C). All my laptops these days use it (including two Chromebooks, a high end MacBook, and a Windows laptop) and of those, only the Windows laptop even had USB-A ports (ie, the other laptops only had USB-C).
I won't pretend it's perfectly ubiquitous. There's lots of older electronics still using micro or mini USB (there's been no reason for manufacturers to update older devices). But it's definitely common in my book.
Sadly yeah. We absolutely should use email signup because it filters our the absolute lowest effort bots, but it does nothing against higher quality bots or humans. Not only can you easily spin up new emails on the fly, but many emails allow ways to make the email appear unique (eg, Gmail ignores dots and anything after the + sign), there's plenty of temporary email services with a variety of domains, and if you own a domain, you can trivially create unlimited emails until they catch on and ban the entire domain.
Inactive admins are also an issue, but if malicious users are determined enough, it doesn't matter that much how active an admin is. An active admin can mostly help by making IP banning an option (imperfect, but will work on many humans) and can temporarily turn on approvals to make it easier to weed out low hanging fruit. Nothing will work against someone determined enough, but could at least reduce how many instances they can turn to.