Despite the fact that I like Spalletti (I also agree on what brehme said with the right resources he might win the Scudetto with us and definitely believe he'd do well in Europe), letting him go after 2018/19 was the right move, cause the moment he'd fell off with management and players, there isn't many chances to come back from that.
However, I definitely won't say Icardi issue is on him, Icardi issue is on Wanda.
I also don't blame him for losing Zaniolo, because that was the year, we made top 4 again and Roma fell off top 4.
I share the same sentiment as IL Drago in terms of "For me there are zero regrets towards Spalletti even if he ends up winning the title with Napoli."
The same feeling as not keeping Bergkamp, sometimes it is just the right man at the wrong time and place, keeping them, they won't be any good, but you know they will shine if you part ways with them.