North of the Border
There are no bevelled firmer chisels in the chest, no fishtail chisels, and no skew chisels. I don't find these things necessary for making dovetails.

Agreed!

I may not cut dovetails as quick as Rob Cosman but mine -- taking twice as much time, perhaps or more to complete -- are as good as his when all is said and done. Gap free 99% of the time, probably 99.5%. And I have never used any chisels other than regular bench chisels to cut all my dovetails.

To say skew or fishtail chisels are helpful, I agree. To say they are necessary, I smell a sales pitch.