Yes. It's not enough to bring the team out as champions at the end of the season. I think just maximizing the existing squad is also not enough to convince a team to come out as a winner without any additional new ammunition that is considered suitable for the coach's game strategy.
Allegri is known to have cold hands but so far it is rare to hear the names of famous players who come to AC Milan, only Modric who has definitely joined after the FIFA Club World Cup finished strengthening Real Madrid. Modric came but Reijnders left.
Yes, that's what Milan should do, perfect the team by not selling players who have a positive contribution to the club. However, not with Milan who often selling players who are on fire. Many fans including me, were disappointed with Reijnders move, he was still young and a player who performed well last season and was replaced by a player who was quite old. Indeed, Milan needs old players to be "advisors" for players on the field. Milan without old players is like not Milan. This has become a culture at AC Milan that always brings in old players. Not to underestimate Modric ability, but he may not be a player who can play all 38 matches for 90 minutes.
It is the custom of Milan to take players who are a bit old but still very good, now it comes to mind when they gave away Pirlo who at Juventus made a panic, however cheerful he can do very well and manage this wonderful group, lately Milan is not having a good time, but as I say cheerful can do very well