Those players were not free. Can's sing on fee was 16m or something, cannot imagine Ramsey and Rabiot were (much) lower.
McKennie and Arthur were more than 40m together plus huge wages for Arthur.
And midfield signings only do not determine that.
We spent 40m on Cancelo the summer we signed him, then 80m on De Ligt, 18m on Demiral, Chiesa and Morata not on cheap loans, gave money to Matuidi, Higuain, Mario and Khedira just to leave etc. Kulusevski for 44.
We changed 80% of the team in two years ffs, this is not a team that is penny pinching. We were never the richest, but there is no way we could not have spent 100m or so on midfield. We just decided not to and spend it in other positions.