Of all the complaints about YAML, I never understood this one, which is actually the correct way to handle it. Of course N.M (without some kind of quotes) is a floating point number and not a string!? The other way around would be _really_ strange.
On a general case, yes. But we are talking about Stack, a system for managing software dependencies. When was the last time you put numbers intended to be real numbers in a dependency declaration file? In different words, when was the last time you added, subtracted, multiplied or divided versions?
Version numbers are always strings with special comparison semantics.
My point is that all the numbers in a dependency configuration file should be automatically converted to strings, because they are really strings. Yaml doesn't do that.