One you cherry pick SPA attempts, like with Twitter. This is an example of a company trying to refactor for SPA, not doing SPA from the beginning.
Libraries that help with SPA are maturing. It's easy to implement routing with backbone for example. You just have to be a good developer and actually learn.
The part that really matters is being a solid dev. Not if you choose SPA or not.
One you cherry pick SPA attempts, like with Twitter. This is an example of a company trying to refactor for SPA, not doing SPA from the beginning.
Libraries that help with SPA are maturing. It's easy to implement routing with backbone for example. You just have to be a good developer and actually learn.
The part that really matters is being a solid dev. Not if you choose SPA or not.