People need to stop basing their opinions about general gameplay on Pro tier lists.
Pro tier lists are ranking characters according to how they fair on an organized team of players who practice together and have active team-coordination in game via communication and strategies/responses.
The games that 99% of you play are solo queue games. You jump into ranked or QP, maybe even with a stack of friends, and you play. Probably the whole team is not on mic, there's limited communication, and absolutely no-preplanning or strategizing, just trying to make it work with the players you have together in the queue. You are not coordinated and are attempting to put together coordination on the fly to enable your team mates as best as possible.
This is why, if you play Squirrel Girl, go ahead and play Squirrel Girl unless you're getting hard countered or something. Just because the pros rate her as F tier, that really doesn't affect you in the slightest and people claiming any character that is F tier on the Pro tier lists is a throw pick or unplayable in their QP or Gold matches is just a bot forming opinions on information they don't even understand. SG for example is F tier in Pro because they can aim and coordinate so get much better value with other Poke DPS while easily just shooting her from afar.
On the other side, just because you see Wolverine or Captain America ranked as an S tier Pro level character, doesn't mean you're gonna just pick them up and dominate. These characters specifically are extremely good because they are excellent with team coordination. If you try to play solo queue Wolverine in your ranked matches and your team doesn't shoot who you grab or heal you when you pick a tank, you're gonna get roasted. Likewise if you can't coordinate your pressure with Cap according to your team's flowing situation, you're gonna be more like an A tier or B tier tank on your team.
This is becoming a relevant divide because a whole lot of people are claiming that Dino being S tier by Pro estimations means that they can't possibly just easily counter him at their casual level. Dino is excellent at Pro level because Pros are specifically orienting their team comps and strategies around any exploit they can find in the game together to play around. You are just being run down by a Dino because your positioning is bad and you're trying to 1v1 a Brawl tank as Mag.
tl;dr - The tier lists you people are claiming as Bible are often barely relevant to your gameplay experience. Play who you want and don't argue about non-Pro play based on Pro lists. Characters that Pros say are "broken" at their level are not at your level.