As a developer with 7+ years industry experience this is a very weak excuse to not support browsers.
Differences in features are usually down to bleeding edge stuff and I don’t think your example of sort would apply because the end result is the same.
I know Adobe are more prone to using newer browser features but there really shouldn’t be anything that’s not simple enough to assure support across all browsers. Especially for a company as big as Adobe. It’s inexcusable. We rarely have to use polyfills now, that was more a problem when I was starting out, mainly due to IE11 still holding out.
Yeah sure, fine for the SME sized business and I’ve done it in the past for features like offline web behaviours (wasn’t public facing). But tbh it’s a shitty excuse even at that size and outright inexcusable for Adobe. I wouldn’t get away with this at my current place which has significantly less resources than them. Don’t make excuses for Adobe and it’s a weak excuse at best.