Is "tantamount" only for negative things?

Question

Is it possible to say "A is tantamount to B" where B is not a negative thing?

Can "is tantamount to" be used with neutral or positive things, as a perfect synonym of "is equivalent to"? Or is it incorrect / awkward?

Answer 1

Cambridge Dictionary says that 'tantamount' means:

being almost the same OR having the same effect as something, usually something bad.

This conveys the following information:

Tantamount can mean nearly the same as something (not just exactly the same)

Tantamount can mean 'having the same effect' as something.

Tantamount is most often used negatively, but does not have to be always used negatively.

Tantamount (Cambridge Dictionary)

Merriam-Webster gives this meaning:

equivalent in value, significance, or effect

That dictionary gives this positive or neutral example:

a relationship tantamount to marriage

Collins Dictionary gives this meaning, which is unequivocally negative:

If you say that one thing is tantamount to a second, more serious thing, you are emphasizing how bad, unacceptable, or unfortunate the first thing is by comparing it to the second.

Longman gives this positive example

For campaign strategists, this was tantamount to spinning straw into gold.

Grammarist gives a neutral example:

we could say that a pitcher of beer is tantamount to a six-pack.

Psychology Today (neutral/positive):

While optimism is not tantamount to happiness, optimists and the very happy both have strong social networks.

Summary: You can use 'tantamount' positively, neutrally, or negatively (there is sufficient support), but be prepared to defend a positive or neutral usage if it is criticised by people who have only looked in one dictionary, or who are convinced of it only having a negative implication