I don't think that happens. You might lose access to features and multiplayer, but not the games you own.

At worst, you cannot buy more games or gifts or trade your items. But you can still download the single player games you already have.

EDIT: Generally it seems account suspension is possible, but that usually means they noticed something illegal or extremely suspicious activity.

That sounds odd, because how does your steam account even get banned? If you cheat in a game and get banned, your steam account isn't banned

AFAIK most horror stories are from people who move between countries, particularly from one with "cheaper" prices like Argentina to one with more expensive ones. Not sure if the account itself gets banned but the games previously bought do get locked out.

Back in the day playing on VAC servers and attempting to use exploits would get your whole account banned.