Keep in mind it'll have a double impact though: not only will autofill spit out a bunch more support players, it'll also mean faster queue times for everyone (including non-supports), so people will be available to get back into queue again (and making it so those mid/top people are more likely to find matches before they get pushed into autofill times).
That said though, autofill is unlikely to apply to you, at least not on that account. It's only really a thing for those with super long queue times, which is only the case at the extremes of MMRs (as in, diamond+).