The 'one format' thing is actually somewhat of a problem. Users may want to be sure they're staying loseless when doing an operation and with most modern format

The 'one format' thing is actually somewhat of a problem. Users may want to be sure they're staying loseless when doing an operation and with most modern formats one can't ensure that. Yes, lossy PNG can be done, but in such a way that there's no way to apply that transformation without being very aware - but there's no similar standard to ensure this with modern formats, this is left to the mercy of software.