I have an old MacBook Air that my daughter uses for school; it doesn’t support the evergreen version of MacOS/Safari, or Firefox or Chrome. I think Proxies have been around long enough that they are supported…but I’m waiting for the day that she can no longer use a browser on that machine, at which point I’ll either have to buy her a new one, or install some flavor of Linux. It’s a shame because the computer itself is totally serviceable!