Honestly, the worst poker advice I've ever heard is: "Just play tight and you'll always be profitable."
It sounds good on the surface, especially for a beginner, but it's a terrible long-term strategy. It's like telling someone to "just eat healthy food" without explaining that a varied diet is better than just eating the same salad every day.
Here's why it's so bad:
You become a statue. If you only ever raise with aces or kings, everyone at the table will know exactly what you have. You'll never get paid off on your big hands because everyone will just fold. They'll steal your blinds all day long, and you'll bleed chips while waiting for a good hand that no one will play against.
It kills your bluffs. A tight image is great for bluffing, but if you're always tight, you never get a chance to use it. You're so predictable that any aggressive move you make is seen as a sign of strength, and people will just get out of your way.
It ignores position. A tight strategy says a hand like 8-7 suited is garbage. But if you're in the last position and everyone has checked, that hand could win you a pot with a simple bet, or hit a monster flush or straight on the flop. A strict "tight" strategy makes you pass on all these opportunities.
In short, it's advice that gets you to the starting line, but leaves you there while everyone else is running the race. You need to be dynamic, not a robot. You have to be able to mix it up and occasionally get out of line to be truly successful.
I needed a long time to learn this. Thought I controlled the noobs but in fact they always folded when I bet. Had to learn to find a mixed way of playing to become less transparent.