[2021] Is there a problem in picking Teemo Baron lane?

Yeah, you should play the champion you want to play. Someone on my team is a terrifying top lane Teemo. It is a legit pick, and you should play what you think will help you team win. Keep in mind not tilting your teammates is a factor in that, so don't be a jerk about it. :D However, if you legitimately think you can win the match up... well, haters gonna hate I guess. Broadly speaking we're not going to penalize players for off-meta picks or unusual champion choices as long as you're playing to win. What we will penalize you for is being a jerk to your team (say if that person has said "no Teemo, or I feed") or intentionally losing/playing poorly.