That’s one reason to use Steam, though.
The other reason is when you buy stuff ( Omega time ) it keeps a record of the transaction, sends you a mail, keeps your settings so faster next time to use the store and you have proof of purchase in case something goes wrong so you have something to put in the ticket for support people to figure out what happened and redress the situation.
Steam also accepts PayPal which is one of the best thing to use to pay anything for online. PayPal saves everything and allows you to contest a payment if you get ripped off.
I play all my games with Steam and pay everything through PayPal. Been doing that for years and have no complaint whatsoever.
PS: You also get discounts through Steam once in a while. Forgot to mention that. Last time I got 3 months Omega and got PLEX for it plus a discount on the price.