I think that you're missing the point. As someone posted already an answer, Osclass is using a non-default extension, unlike vanilla WordPress that does and will work with most newer PHP versions "out of the box". In those cases, when you use something which is not default, must be included in the requirements.
Also, enabling a lot of unnecessary extensions just because you can, does not mean it's smart. In fact, in my opinion, a good shared hosting will initially provide you only with vanilla php version, and later enable you to customize/expand it per your needs. There are 100s of extensions out there, do you (your hosting) really have them all enabled? I doubt it.
Anyway, it is a pointless discussion really, as the fix is already proposed and requires minimal changes in a single file.