[Leherenn]

I had the same reaction at first, but after a bit of thinking I reached this:

You can do without it, sure, but if you don't have a bidet then it's inconvenient and annoying. Toilet paper is cheap, easy to store and it does not degrade (in a meaningful timeframe).

Basically, unless you are really space constrained, there are no downsides to having more than needed, so why not buy extra?

I say this as someone who had to go without a couple days because the stores had been cleared of any toilet paper.