Yes and no. Things get mastered mostly because that's the received wisdom. "You have to get your track/album mastered before release." Steven Wilson's body of mixing work is proof that great sound is possible without mastering. Sometimes, heavy-handed mastering can get in the way of a great-sounding, balanced, tonally pleasing, dynamic mix.
Some of this is miscommunication...
Mastering is simply putting a mix into a consumer container.
The only reasons for that process to ALSO include altering the audio is either to cater to lower quality 'containers' or because there may have been a problem (in someone's humble opinion of course) with the audio. Now, if someone goes pulling and tugging on a finished mix instead of going back to the multitracks... If the mults were lost, altering the final mix would be the only choice. If not, someone is being lazy or cheap or both.
Of course then there's the stuff that seems like it was intentionally degraded. Is that intentional to make for a future "upgrade"? Is it simply that the C- engineer got the job that day? Either of those explanations sounds silly but I don't see how there could be a 3rd choice.
Back to this While Album REMIX...
In this case, the treble hype doesn't match up with the mixing work. The mixing work here has an excellence to it. The treble hype slathered on top of that is shockingly crude. This was NOT done by the same hand! Did someone really give excellent work to an intern to finish? See, this is what makes the more conspiratorial explanation of intentional degrading it kind of seem more likely.
Anyway, if you reduce the high end above 3750Hz it brings this more into proper balance and you can appreciate the mix work done here. The original stereo is still definitive and has better fidelity but this remix has a reason to exist.
FYI, The high end boost someone did likely involved some compression. So just turning it down seems to maybe step on it a little at the end of the day - depending on the eq you might be using and so forth. I put this master on one track on the mixing board unaltered and then blended in a 2nd copy with all the highs above 3750Hz rolled off with a linear phase crossover eq. Original unaltered track at -1.41db and the low&mids boost track at -16.3. That gave me a proper balance (IMHO) with no clipping (with no compression or limiting).
This is a well done mix. At least worthy of being an alternate choice. Certainly some isolated areas of improvement even if the original is still definitive.
However, if I were to vote on this, the part where it looks like it was intentionally degraded would have a lot of weight in that vote. Just sayin