DH of ginger, I think that there is a balance.
I agree absolutely that when it comes to genuine Maths problems, speed is not an indicator of ability in any way. However, 'automaticity' of certain trivial elements within the calculation of the solution to the problem means that time and attention can be given to the real problem, if that makes sense?
If we look at an analogy with English, the best writers are not those who fill the page quickest. However, having to sound out each word because no spellings are automatic poses a barrier to being the best writer that someone can be.
I think there is a level of 'automaticity', of recall rather than calculation, that is genuinely useful for key number facts such as times tables - by analogy, a number of words, like 'and', 'but', 'with', that it is genuinely useful to be able to write without thinking about them. However, there is then little or no advantage of being 'even quicker'.
For example, I can spell 'and' without thinking, but have to pay attention to which of practise / practice I need in a specific context. The poster above knows 5x7 automatically, but has to do the extra step of adding 7 for 6x7. That is an 'useful level' of automaticity, and is very significantly better than counting up in 7s from 0 every time, because if someone has to work out every fact on every occasion, the amount of time or effort that can be addressed to 'the real problem' is reduced.