I'm not sure why so many are so set against it?
Forget Maddison/Alvarez/Patrick Viera (he's on a free now)/Pirlo etc. - whoever it is, we're probably looking to bring in a quality CM and someone like McTomminay.
Forget about the money - we are rich as... and can be buying squad players even if it's £20-30m on a player to "compete" for places and who isn't a guarantee starter. If we make Europe we'll have even more money to spend thank most are thinking and more commercial pulling power.
There is a space to fill, even with another, top end, CM coming in and it's no good not having a player there to fill it? The other options are Hendrick, Hayden, Matty Longstaff or youth... If we are playing in Europe you are looking at 46 club games minimum next season (if you went out at the group stage and first round of the cups) possibly up to 60-70 if you progress through the cups (potentially 12-14 games - excluding replays) and Europe (potentially 9 games after the group stage) and you need a squad to play that many games. Plus a lot of our players are now internationals, Pope, Trippier, Schar, Botman, Bruno, Miggy, Isak from the starting line up alone so some of them will be looking at 40+ games in a season in a high intensity pressing team for the majority of the year.
If we get another serious injury like and ACL to someone like Bruno and have only bought in one CM we are back to the same situation we are in now, worrying about a pulled hammy or a sending off.