I don't think the chance of cheating is a serious issue if you're playing at a low level online. You're generally matched against playes with a similar rating, and someone using a computer heavily would drastically inflate their rating. Which also increases the chance at detection significantly.
Computers are scary good at chess, it's not exactly invisible if you use them to cheat. If you're a beginner it's also quite hard to understand why the computer makes certain moves, so if you just sprinkle in some computer moves in your game it's likely you might just fail to capitalize on those moves because you don't understand their purpose. The computer also plays some quite non-human moves at times, which is also likely to draw attention if someone is cheating a lot.
I'm not saying people don't cheat online in chess, but I don't think it's anywhere near prevalent enough to ruin the game.
Computers are scary good at chess, it's not exactly invisible if you use them to cheat. If you're a beginner it's also quite hard to understand why the computer makes certain moves, so if you just sprinkle in some computer moves in your game it's likely you might just fail to capitalize on those moves because you don't understand their purpose. The computer also plays some quite non-human moves at times, which is also likely to draw attention if someone is cheating a lot.
I'm not saying people don't cheat online in chess, but I don't think it's anywhere near prevalent enough to ruin the game.