The thing you're missing though is that as $NEW_THINGs get more popular and more people try to implement them, they do it badly, spread their bad implementation

The thing you're missing though is that as $NEW_THINGs get more popular and more people try to implement them, they do it badly, spread their bad implementation as gospel, and that actually changes the popular definition into something barely recognizable that becomes $OLD_THING. A few smart non-graybeards eventually play around with $OLD_THING enough that they actually stumble upon the original definition of it, but don't realize that they are really just rediscovering the original definition. So of course they (re)name their discovery as the next $NEW_THING. Then cue the graybeards. SOA is really just object oriented programming. Microservices is really just object oriented programming. Object oriented programming is really just dependency management.