it's not at all difficult to run code written for angular 1, python 2, gtk 2, gtk 3, or x11; you don't even have to port them, you can just run them, and i do every day. it doesn't even require any effort
contrast that to applications written for silverlight, activex, or flash
with respect to gtk 1, you sort of have a point, but gtk 2 was released in 02002, and it's usually not hard to port gtk 1 apps to gtk 2 (and almost all of them have already been ported). and i'm not sure what you mean about 'old kde'
free software licenses provide strong legal protections to users to do whatever is necessary to maintain and extend the software they depend on and share that with others, and in practice they do, and the consequence is that the hype cycle is much slower and less destructive
