Fungus is not as bad as people make it.
I have cleaned a lot of lenses at work, mostly Zeiss Jena and Meyer Görlitz, maybe half of them had fungus.
Technically, yes, fungus etches the glass but not always.
I have seen lenses full of fungus which cleaned out just fine, some had only a tiny spot and the spot remained a spot, even when cleaned.
It depends and I can never say if the lens will be fine after cleaning or if remains of the mycels can be seen.
Throwing lenses away which have a little fungus in them is idiotic IMHO, the fungus in there comes from the spores in the air we breathe.
Are you going to throw you lungs away because they have fungus spores in them? The immune system takes care of that.
I have bought lenses for my own personal use which had fungus in them, I cleaned them and as I said, used them. I have never seen any difference in the pictures from non-etched to etched lenses.
For a while I used a beaten, ancient Nikkor 3,5cm 3.5 I believe, it had scratches on the front element, I have never seen loss of contrast or anything else that would make me get rid of the lens.
"User condition" lenses or the ones with fungus tend to go for a lot less than perfectly fine ones, if you know how to repair them you can save a lot of money.
I store my cleaned lenses in the same cupboard as my other stuff and there is nothing of fungus to be seen.
If you are not sure wether you've killed all of the fungus spores in your lens, take it out shooting. UV light kills fungus spores.
No use hoarding lenses if you're not using them.