Thing is, old options did not go away. If you really want to, you can still build perfectly fine websites with PHP, with no frameworks. But new things come and people learn them because they are easier to use and easier to maintain, and because it's a challenge and fun to learn new things. So ultimately it depends on you (or your employer), whether you wish to invest in a new set of tools or not.
My second point is, it's not just web development, it's everything having to do with computers. Knowledge of Commodore 64 peeks and pokes is quite useless today, I wouldn't touch Fortran with a ten-foot pole again, and Java 1.6 is quite different from 1.3 when I started messing with it. My first PC had 1Mb of memory (I was lucky, my friends had 640Kb), and it was quite important to know the difference between extended and expanded memory. No more. And knowing how to draw something on a monochrome Hercules card has absolutely no bearing in the world of OpenGL 4.0.
The only thing I can tell you is, pick what interests you, or pick something you think will come in handy, and have fun with it. If new things come along, be happy that you'll have a new toy. Anything else, and you'll be stuck in the past, doing things the stone age way.
@Coronatus: Why do you think Rails sucks? I found it quite pleasant to work with; and given choice of Ruby framework and PHP framework, I'll always pick Ruby... Of course, that's subjective, but I found your categorical statement a bit... ridiculous.