Why are Jungle and Top the new autofill?

Look at the question above.

Now I´d like to know why this is the case, because that´s a huge problem for me. Autofill in general is not a bad thing. Unless it´s ranked. My point is, speaking for myself only, I can cover 3 out of 5 lanes/roles in ranked. I even queue as a secondary Support main. But lately autofill has ruined my ranked games cause I get neither of my 3 main roles, but my two unwanted roles. Yes I perform poorly in these roles, yes I´ve tried to learn them and I don´t enjoy them. Jungle and Top are my problem areas.

I´ve been playing since early season 4, which is not really impressing but nonetheless quite some time. Support has always been a lackluster role and I always filled in when needed. Even when autofill became a thing I still played support secondary and filled in when I had e.g. Bot and mid.

But now that support has actually become a decent and popular role I hardly get it anymore. Autofill always ends in my worst two roles and I almost never get to switch with someone else, because few people want Jungle/Top anymore.

TL;DR - Why does no one want to play these roles in ranked? Am I the only suffering in ranked because getting stuck on the only 2 roles they can not perform well on? (3 out of 5 is a pretty good tendency after all)