I used to think like this, but nowadays I think that's no a real problem, at eñadt to me. I find it very easy to go across different JavaScript projects with different libraries, etc. Usually the worst part is understanding the business domain, the warts of the application, the know bugs, problems, etc.
The libraries used, as long as they have documentation and are supported and more or less widely used...that's fine, they're easy to learn. And if I have to switch between 10 different projects, then for me that's the actual problem, not the fact they have different architectures.
What has been a terrible experience for me, was when at two past companies in an attempt to "standardize" they ended up with custom in house libraries and wrappers, all of them built in house, undocumented, with the original developers already gone and nobody knowing/wanting to touch them. And then the rejection of any kind of improvement or modernization because "then that new app will have a different architecture"... So what? We have a terrible one, and we need to do every project terrible, so everything is consistently terrible.