Yeah I'd imagine everyone we signed would have still joined. But being in the CL is clearly important if you want to sign players like Ozil and Sanchez, and if you want to keep the ones you already have. If we want to sign any Barca/Real/Bayern surplus players, which is about as good as it gets for us, then CL is pretty damn important I'd say.
I thought you were using the example of Mane to show that clubs outside the CL can still attract quality players, maybe I misunderstood or missed the nuance of your argument.
I won't be devastated by being in the EL, unlike others I'd want to take it seriously and win it, and truth be told I am more than a little bored of our CL campaigns, but overall I'd rather we still played in the CL because it gives us the best chance of keeping our best players and signing some more really good ones.