That's the reason why it's not conducive to building a team. It was a numb nuts appointment and it's costing us not only an arm and a leg with =his salary but also costing us our best talent walking out the club.
Lukaku would have gone last summer if not for Koeman. As it is, he's stayed, improved, and will go for a higher fee this summer.
Barkley is a trickier one. Yes Koeman hasn't been all that great for him - but he's been offered a contract and he's holding out for more money. The ball is in Barkley's court not Koeman's.
As for whether Koeman was a good appointment or not - we are 1 year into his 3 years and have improved a lot - despite a bungled first transfer window.
On moshiri (just read some of your many negative posts elsewhere), you can't pin Lukaku leaving on him as a broken promise. Yes we sold stones - but followed that up in January with over £30m of deals. The spending will come. But But stones and lukaku wanted to leave way before Moshiri was here. Selling them doesn't mean he's failing or asset stripping. Moshiri inherited a club hat was badly underperforming, and sometimes it takes longer to turn around a club than a big player will wait. We've lost stones and we will lose lukaku and maybe Barkley but I think long term we will be stronger under Moshiri.
That said, I expect us to miss out on lots more players while we are not a CL team.