Hello Simon,
Yes you're absolutely right.
Often, things, that are very true (!), are said about things, like lenses. Repeats of things heard before, somewhere else. Etc.
But equally often they are repeated without citing the proper context they belong in.
Many things (all?) are relative (i know, it's platitude No.1).
And that makes all the difference.
Like the 120-mm-soft thingy: its performance at infinity is indeed 'soft',
compared to (there's the relative bit) what this same lens can do at another distance. But people only remember "soft at infinity".
Compare it too, say, a CB 160 mm and 'soft' takes on a completely new meaning.
There's another form of relativity involved too. Some people like to use 'soft' lenses for portraits, but i love portraits that show every pore.
So what is 'better'?
And another relativity related thing: lens performance is relative to 1) our ability or inability to use the potential in a lens to the fullest, and b) our need for all that, the "more than enough"-thing.
Using a lens handheld, at 1/30, while running the final 100 m stretch of the Athens Marathon, in 40 degrees centigrade heat, without having taken fluids for the last 40 km or so, or using the same thing on top of a cheap tripod. It will make a huge difference.
I know, that's not about how good a lens is. But if that like in that first thing is the only way you ever take pictures ...
And should we really worry about one lens being better than another, when both lenses we're comparing &ly fullfill our lens performance needs already?
So, again, yes, you're absolutely right.