Why limit level of gems?

Hello,

some of the guides indicate to use a certain skill but not level it beyond X. Why is that? Is it to avoid having to worry about int/dex/str or something else?

Thank you.

There's a number of reasons, including stat restrictions.

Most common one in the guides is the 'Cast when damage taken' setup. Every time you level it up, it increases the threshold at which it triggers (how much damage you must take before this triggers). A lot of builds want this triggering as often as possible, so they keep the level low, keeping the threshold low.

If you link this gem with, say a curse, you'll need to keep the curse level low too. Too high and this gem wont trigger it anymore.

Hope that clarifies.
~Myth

Yes it does, thank you.