This premise fails on a number of levels though. Yes
removing a Malz ult would make Malz almost worthless against that particular champion, but there are still 4 other people Malz can utilize his ult on to full effect. Further, if someone is taking
to counter Malz, that means they aren't taking a more universally/globally useful summoner such as
,
or
, which can be immensely important throughout the match.
On the topic of item slots and QSS, its almost a moot point in the games current state because its rare for games to last long enough for people to reach full build anyways. But even still, people typically try to build at least one defensive item anyways so QSS simply takes up that slot. If they build it early then it might delay their damage a little bit but its not exactly an expensive item so a good farmer will hardly notice. This on top of the fact that AD champions can build it into a damage item anyways, allowing them to have an "offensive-defensive" item thereby allowing them to build another defensive item as well.
The same as above is true for Zhonyas, btw. If you build it instead of a more standard defensive item (GA, Banshees, etc) the fact that its AP is almost irrelevant. It still provides armor for defensive purposes on top of its active, and some AD champions have abilities with AP scaling (such as Lucians W) so that buying a Zhonyas on an AD champion is entirely reasonable.
At the end of the day though, if
doesn't remove Malz ult (and other suppression ults) then Riot should update its description to clarify its usefulness. I made a post about this very thing a day or two ago because I, as
took
against a Malz because the spells description says that it removes ALL DISABLES. If it doesn't do that, then the spell is basically misleading people into bringing a useless ability into a game. The only way to know that
doesn't remove a certain ability is to...already have that knowledge. I shouldn't have to screw myself in a match in order to find out how a spell works.