I re-watched the whole MASH just few years back and you are right. That show walks on that exact thin line... Honestly I think Alda did an amazing job conveying the strongest anti-war message in the lightest possible way.
Discussion
Mash is awesome. But it goes from lighthearted fun down very fast. I stopped rewatching it quite soon, it started to be so..on point I guess. Alda's humor just made it worse for me, not because it was bad. It was very good and very hopeless. It's very good show. And listening to those theme song words for once didn't do anything better.😑