They may look good, but they tend to break things like back/forwards have text that can't be copied and pasted.
Some have embedded video, which eats everything.
That's not a requirement for building a single page app, there have been ways of emulating history in spas for a while now.
> have text that can't be copied and pasted
What do you mean? SI'm not aware of any sites whose text 'can't' be copied unless they disabled right clicking.
They may look good, but they tend to break things like back/forwards have text that can't be copied and pasted.
Some have embedded video, which eats everything.