Probably the nub of the issue. £60-70m on players with no resale value is difficult to justify when, upon looking at City's squad, you realise that whether you sign those players or not, your chances of winning a big pot remains more-or-less the same (ie zero). With no chance of ever making your money back, you're effectively throwing it away on a lost cause.Matic and Zalatan were both sensible signings in every respect. If we could get Perisic and Willian for ~£30m I'm sure we would. But if they had cost upwards of £60m like Willian and Perisic I doubt we'd have gone near them, and rightly so. I can understand the board not wanting to spend huge amounts on older players. It's a poor investment, unless you believe either of those players will be the difference between winning the title/CL and not winning.
I just hope that if the plan is to 'sit it out' in the top 4, biding our time until City's cycle of dominance comes to an end, that the board are at least slightly cognisant of how challenging even that meagre target will be with resurgent Liverpool/Arsenal/Chelsea sides and Pochettino's Spurs all fighting for the same places. Standing still is going backwards here.