Honestly, I think I prefer not having access to something like Pinterest[1] which lets you have some access for a bit and then as soon as you try to interact with the site in any meaningful way (usually to leave it) they insist you sign in.

At least with this I know the expectation up front, rather than having it sprung on me by surprise.

[1] I've avoided Pinterest for awhile that this may not be the way they attempt to capture accounts any more.