We do not often use

[suprunp]

"We do not often use the present perfect with words that refer to a completely finished period of time, like yesterday, last week, then, when, three years ago, in 1970.
(Practical English Usage, Michael Swan)

I wonder why the author says 'do not often' (~ sometimes) when we do not use the present perfect in this way at all, do we?

Thanks.

[Tdol]

Absolute rules rarely work perfectly- describing things as tendencies is often safer and more accurate.