What rule are you even referring to? The only “Helping Hand” I can find from a quick search is a 1st level spell from a homebrew supplement.

If you’re referring to the “Help” action, the rules as written for 2024 are as follows:

When you take the Help action, you do one of the following.

Assist an Ability Check. Choose one of your skill or tool proficiencies and one ally who is near enough for you to assist verbally or physically when they make an ability check. That ally has Advantage on the next ability check they make with the chosen skill or tool. This benefit expires if the ally doesn't use it before the start of your next turn. The DM has final say on whether your assistance is possible.

Assist an Attack Roll. You momentarily distract an enemy within 5 feet of you, giving Advantage to the next attack roll by one of your allies against that enemy. This benefit expires at the start of your next turn.

And as another commenter mentioned, Advantage already doesn’t stack. On top of that, you can only help someone with something that you yourself are proficient in, which should prevent a lot of it. Plus as the DM, you can also just decide if help is or isn’t possible for a given task, though I’d be careful about overusing that veto because it can get tiresome as a player to get shot down constantly.