The problem is, that the people who 3bet a little looser are generally going broke lighter postflop.
You're usually aggressive postflop when you flop equity - with a hand like T9s having equity usually means we're on a draw which means once we're on the flop we have the equity to get it in but we're still an underdog.
If we have some foldequity the overall-play is +EV, but that means we need to know some tendencies of the opponent to generate this foldequity.
For example if we know he cbets a lot and gives up afterwards we can either float with equity and take it down on a lot of turns or (semi)bluffraise the flop.
If he 2ndbarrels too much we can take a call flop, shove turn line.
Etc...
Ofc you can do all of this vs unknowns too, but it's speculative and we end up making mistakes by playing back and creating big pots based on assumptions.
So I much rather play tight and once I know he's 3betting a lot start calling hands with highcardvalue (i.e. expanding the callingrange with hands like AQ, AJ, KQ, etc.).
With SC's my rule of thumb is ~120bb.