so i am a top laner, atleast i mained top, but when i am in solo queue top lane is almost always, so because i dont want to fight with my team, i will just play the role no one wants, most of the times support.
not that i am a bad support(i play a lot of zyra and nunu) but then other lanes start feeding and people start flqming untill eventually we lost,
well this happens me on draft all the time(im not playing ranked for amehile due the elo reset and all "pro's" and "noobs" beeing in the same game )
If you duoq and you are higher elo, then you are more likely to be first pick (or at least not last pick). On the contrary, if you are lower elo than your mate, you'll be last pick most of the time (and thus support).
If you don't duoqueue, then statistically you will be last pick significantly less than 20 pct of the time (because you are likely to be matchmade with duoqueurs that will take this place).
If you don't get the role you want, then dodgequeue.
But last advice : try and play the five roles correctly, if atm you are a good toplaner, try and play jungle for 50 games, then mid another round, then ADC ... This way you'll know better what champions you are confident with for these roles (instead of locking whatever you feel like, sort of) as well as being more experimented in general (knowing matchups, harrasing better, feeling how to position with X role, ...) .
In my opinion queue dodging isn't the greatest advice unless 100% necessary e.g troll picks, if I recall you get slapped with a debug from queuing for any sort of game and instantly slapped with -10 elo which is a pain in its own right considering trolls and bad players are punished only by the loss if they don't themselves dodge. (info based on the player who went -4 - 1500 via queue dodge method)
Yes you definitely can main something in solo que, it just doesn't mean that you get to play that role each game.
Im a pretty terrible jungler, and not really fond of supportting (aside of blitz which Im pretty decent with), but Im doing really well as top. My mid and ad's are very fine aswell, but very limited to certain champions as a result of lack of play.
To OP: It's way harder to get one spesific role each game than try not to get two roles you suck at. Try it out, and practise atleast two or three roles very well :)