So my understanding based on some of these responses is that while we have the best solution within reach, we should instead live as if that solution is not within reach? Back when we had the old system I also would advocate knowing at least 2 champions in every role, because it was expected that you'd have to fill each of the 5 roles at some point (and in spite of that I very rarely played mid/adc, and I still suck at them, proven by how poorly I usually did if I were forced into those roles, especially ADC, at least in Ranked games).
Now I've to clarify by stating I've played overall far fewer PvP matches than most people who started playing in late Season 3, so that among other reasons gives me plenty of excuse for why I've played an extremely small number of PvP matches even in Normals as ADC, and only a bit more as Mid making me slightly less incompetent at that role. It's not uncommon that I've seen Diamond players state that you're never going to get truly good at all 5 roles because quite simply nobody has time to do so, at best you can just learn to not feed, and hope to get carried, or that your lane opponent blows more than you do, or has a particularly bad game (lucky for you, since you are not ranked-ready for that role).
I mean, I can easily get Gold or above I'd guess if I only ever had to play Jungle (I can't prove that, but if I played nearly as many games as a lot of other people do, I'd not be surprised to have hit high-plat/somewhere in diamond by now [I've a lot of other interests that keep me from playing/progressing in this particular game, but I'd love for it to be in the best possible/most enjoyable state for everyone's sake, and being autofilled into any of the 5 roles rather than only needing to be prepared for 3 roles just seems really dumb to me]). On the other hand I don't feel comfortable that I'm capable of carrying with any other role, and I don't particularly enjoy any other role so far by comparison with Jungle, but I in the past (when there was no other option) would suck it up and accept that I've to play all of the other roles potentially (and would even try to calm the complaints of others who didn't like it, but showed them I understood their frustration with the poorly thought out system we were forced to operate within).
Now, with the fact that we have autofill, and we have the new champion select, let's not be luddite-minded souls, and accept that we can in fact make it so that you only have to be prepared for 3 out of 5 roles for a given Ranked match. That way people who for example don't have a lot of Rune pages will be prepared for all of the roles that they KNOW they will have to be prepared for. It's A LOT easier to be prepared for 3 roles than 5 roles at any given time. Even if I were once prepared for all 5 roles, which I was early on when I started playing PvP, I found out which roles I didn't enjoy as much, and proceeded to stop playing them for the most part, resulting in that preparedness fading away with time.
Having knowledge of all 5 roles is good, I'm not denying that, and yes knowing how each role functions will improve your game knowledge for a variety of reasons that will make you better at other roles you choose to main, but that does not mean you should then necessarily be forced to play those roles randomly when you're not prepared for them. All that is required for autofill is the Support role (in terms of making Queue-Times short), I don't have the numbers/statistics Riot has but I'LL BET removing anything but Support as something you can get autofilled for, leaving you with 3 potential roles, will only increase queue times by something like 1 minute at most on average.
PLENTY OF PEOPLE would rather play roles they are ready for and enjoy, rather than either be forced to dodge, or play a role they don't want to play for up to 60 minutes of their day. Many people if not most people would be happy to wait an extra minute or so for people to actually choose to be one of the roles that someone would otherwise be autofilled for, besides Support, which should be the only autofill role.
That's why I say, the best compromise for everyone is to only have to be prepared for 3 roles, by making Support the only role that you can be autofilled for, it's simple, it will work, and it's the only way the majority will be happy in the end. To me this is no different to when I was right about Dynamic Queue, and wanted Solo-Queue to return from the time of the inception of DQ. In fact I still want a Pure Solo-Queue without Duos, Duos are free to join Flex Queue.
Anyway, however things end up going, regardless of who or how many disagree with me, as far as I'm concerned, unless you can prove me wrong, and it's not just opinions of yours, I'm right, and I'm a majority of one (assuming everyone disagrees with me, which I highly doubt, but people are free to be a vocal minority and downvote because they lack a proper argument).