Pretty fair point, tbh.
Koeman/Moshiri made the same mistake plenty of teams have done before - he/they bought a bunch of "Football Manager" players with no thought for how they would play together or even fit in the same sodding team, and then sold the top scorer (RL) without replacing him at all.
There's two things that were clearly required in order to 'rescue' the season - someone who could do a job with a team full of misfits, and someone who could easily drop big players and get away with it.
Allardyce did that, and did it well. Yes, the football may not have been 'exciting' or 'attractive', but refer to the above points.
It's all well and good saying "we wouldn't have gone down anyway", but teams with better football and more cohesive players got sucked in and were relegated this season.
I think it's pretty blind to not be grateful tbh - even as an interim.