Raising after 4+ weakish limpers, the leak

[Soepkip]

I just saw a reply of niediam wich said:

The 'leak' isn't just not raising JJ in a mulitway pot but whenever you don't push large preflop edges.

Are you raising hands like JTs and QTs in LP after 4+ weakish limpers? ATs, KJs and 99 out of the blinds? A9s and A8s in LP when weak players enter the pot?

If this goes a lot further than just not raising JJ then this really could be a large leak...

While i would always raise JJ preflop in this situation, a lot of the other things he posted i don't. His post says this could be a large leak and i would like to know the edge in raising these cards. (some i know but some further explanation would be appreciated)

So basically, why would u raise hands like JTs and QTs in LP after 4+ weakish limpers? ATs, KJs and 99 out of the blinds? A9s and A8s in LP when weak players enter the pot

[HoneyBadger]

a) with so many limpers and potential callers of your raise, you often win because of your equity edge. I.e. with 5 people you only need to win 20% of the hands to break-even. If you win 25% that raise wins you money.

b) your raise might buy you the button when you don't have it already. Furthermore it might buy you a free card on the flop. At the very least it buy you initiative. Those pots nobody wants are yours.

c) You expect to outplay your opponents after the flop. You have the button, or perhaps bought it. Position against a field is great. You might get free cards when you have litte, and you might raise the entire field when you're strong.

d) Nobody raised in front of you. Suppose they raise from AT up, then your A8s is also still likely to be the best ace. You might even have the best hand right now.

[Mr. Orange]

You raise cause you have an equity edge. To use one of the examples you listed. ATs in the BB after 4 weak limpers. Assumming the SB calls that's a 6 way flop. You only have to win a 16.6% of the time to make calling profitable. Against 5 random hands your equity is about 26% so you have to raise.
Even if you want to narrow down your opponents hands you should still raise. Say you give them 30% VPIP. Then you have almost 19% equity in a hand you only have to win 16% of the time to be profitable. By putting more money in the pot, your making more money.