[Cthulhu_]

I think it's more of a distinction with 'front-end developer', who is someone that works exclusively on the front-end - e.g. angular, ember, react, etc. This role barely existed 5+ years ago, and every web developer was more of a full-stack developer. Nowadays you could focus only on the front-end side and not need bother with a back-end ever.

[Illniyar]

Actually I see this as reversed, 5 years ago there were a lot more front-end developers (or just web developers then), since it was fairly common to create static sites with little or not interactivity, and if you had a fat client it was in flash (also a front-end only technology, mostly).

I don't think people writing some scripts in PHP would have considered themselves full-stack or back-end.