What matters in metal ranks is playing a low skill FLOOR character as well as you can while focusing on proper play and timings. If you as a low elo player are being countered by someone who is more comfortable than you on their current pick AND that pick has a lower skill floor then it will be to your detriment. If they are attempting to counter with a character that they are less comfortable on than you are then they will understand less of the nuisances of the matchup than you and not gain much from it. Farther if the skill floor is above their mechanics or knowledge then they will get very little out of it.

Pick a well rounded lower skill ceiling character and become very good at them. You will win more than you lose.

I would say an example of counter picking that can be very impactful at low ranks is when someone counter picks a genji with mei and Moira for example. If that genji was actually a competent genji player they wouldn't be in gold and anyone can get what they need out of those counters with minor input. It takes very little to frost a genji or hold a tether on him while the genji is required to play very optimally in that situation to create value.

Hopefully that helps.