Anyone who has any experience with one knows: Vaginas have liquid coming out of them. This is especially true if the owner of a vagina is having sex. Depending on the person, there will at least be some of the liquid coming out of the vagina at some point in the process. Some kind of absorbent padding will almost always be helpful in preventing stains. This is especially important if you think there will be some ejaculation, squirting, peeing, or period blood coming out at any point.
I made this mistake a long time ago when I fingered a woman on her period and got so much blood everywhere when she squirted that it soaked through the sheets and into the mattress, which required bleach to soak into it overnight.
Put something down to absorb it even if you don’t think anything will come out. Something might when you least expect it, so be ready for the flood.
I honestly disagree with you. I’ve used a towel quite a few times with a partner. Hell, I even have a “sacrificial blanket” we used during naughty times. It’s only purpose was to catch the mess I made, and then we would wash it after.
For me, I would much rather just lay down a towel or blanket before hand to prevent having to wash the sheets or sleeping blankets. A little more work up front, but saves a lot of effort later.