Can't . . . resist . . . rant . . .
First thing is that I make a distinction between preference and 'playstyle'. Everyone has preferences, likes and dislikes. This is what people mean when they say they like playing Gengar, or they love Metal decks, or they wish there was a viable spread option in the format etc. Some people use 'playstyle' when they really mean 'preference'. Things like Energy denial, acceleration, spread, evolution, Typing etc aren't 'styles' of play, they are game mechanics. You like some more than others.
I completely acknowledge that it's possible to play in different 'styles'. For example aggressive or conservative. What I absolutely do not accept is that this is connected via some kind of magical woo to a player's personality, and that the best method for them to succeed is by playing in a way that they have decided somehow represents them as a human being.
In fact, I think this is the worst thing a player can learn, because it is a self-imposed limitation. Sometimes it's better to go all-in and play aggressively; sometimes a situation demands a more careful approach with the emphasis on resourse conservation. A truly good player is able to pick up on that, play accordingly, and get better results.
This is about deck choice too. If a slow lock deck is the best choice for a tournament, it's silly to say 'oh, I can't use that, it doesn't suit my aggressive playstyle'. If you're playing for fun, then use what you like; if you are playing to win, then learn the skills you need to play the different decks. It's not that hard. (Ok, it might be for Juniors, but you would expect adults to have better control - not that they always do.).
The way most people use the term, 'playstyle' is a myth. There are only good plays and bad plays.