You can't have "do nothing" mean both "do not accept (yet?)" and also "accept!"; if no action keeps you from accepting, it means it'll take an extra step to actually accept an invitation. If the common case is not trolling, that adds friction.
> The optimal way to use confirmations is often not hitting "Reject" to requests you don't want. Just do nothing.
and didn't read carefully. I was probably pointing out that if trolling is not the common case then that system is not in fact optimal (which I think we agree on), without realizing you didn't claim it was the optimal system but only the optimal system-which-uses-confirmations. Sorry about that.