You're used to getting up and knowing there is still poop there. When you wash with water, it cleans it all off far better than smearing it around with paper. Use your hand and some soap if it makes you feel better. I assume you do that in the shower anyway, otherwise, ewww...

The towel is cleaner than your skid-marked underwear, toss it into the laundry if you think it is still dirty. Heck use old underwear as rags...

I hope you wash your hands before you leave the bathroom. Double ewwww...

There is even a whole wikipedia about the topic:

https://en.wikipedia.org/wiki/Anal_hygiene