So basically, flasks in path of exile are a major power boost. You fill them by killing enemies and can provide huge defensive and offensive bonuses. Like, over doubling your dps for some builds. In general, you're killing stuff fast enough that you never run out of charges, so you're activating your flasks pretty constantly, like every 5-10 seconds. You have 5 of them, so really you're just constantly hitting 1-5, which can be pretty annoying/tedious. People started using macros to activate them on a timer, or so that pressing one button to use all of them. The devs (grinding gear games, or ggg) classified them as cheating. Someone asked "If I taped a popsicle stick to my keyboard so that pressing it pressed 1-5, would that be cheating?", and ggg said yep, don't do it. Lol. They did relatively shortly after add functionality to flasks for auto activation of utility flasks on certain conditions, so you could set them to be used when they stopped being active or when an adjacent flask is used or when you're affected by different status effects, or instead you can have your flasks get a big boost to duration or effect, so they got rid of the problem people were solving by "cheating".