Linux has its own headaches. I have been running Mageia 5, but it has reached end of life. No more security updates, the software repositories have been locked so I can no longer use them to download and install software. I am looking at Gentoo, which is a rolling release so I don't have to install and start over every two years or so. But Gentoo is a right bitch to install. But once installed I need not longer fear end of life. Yes, old computers may have problems, but even new systems can be slow unless you get something built for speed. I have an AMD system with 8 cores, 8 gigs of memory and a decent GPU. It is much faster then my brother's brand new commodity Dell system. Ain't no cheap and easy way out any more. All systems are churning. Windows, Linux with problems of KDE and Gnome regressing, Apple's unfriendly hardware systems. Big changes, not all of them good in the Browser world.
Once I have basic Gentoo installed, I will look at using Virtual Box, so I can play with various OSs and be less dependent on any one of them. I can even run my old Windows 7 and Office 2007 in a VM and not care if it is no longer supported officially.
One big problem is that OS's are getting bigger, web browsers are getting bloated and some websites use lots of memory. Running an old machine with 2 gigabytes memory is going to be slow. Wimpy GPUs will drag everything down. SSDs help a lot but are still expensive.
It is all a pain in the butt any more.