There's not that much to speak on but I'll state the obvious, you pay for a verse from some artist you may or may not even know, to feature him/her on your album that he/she most likely doesn't give a fuck about in the first place.
Right there is mistake number one: A good solo album shouldn't have many features if any at all. So that just shows the artist has little to zero faith in himself or herself and has to resort to paid features of bigger artists in hopes of increasing sales or hype.
Sure it's not a bad idea in the commercial industry and it's extremely common. If your paying someone who sells millions and millions of records, it's clear. But in the "Independent" game, it's a fucking joke. On the flip side your paying someone else to put THEM which also promotes THEM, when in reality your trying to market yourself and make yourself look bigger, it's probably the most fake fraudulent thing a bammer ass artist can do. How can you market yourself when you have that? You can't, your name gets brushed off. It taints your album and reputation as a solo artist.
Mistake number two would be performing shows. Your not completely affiliated with that artist, so you can't just bring them out to a show like it's family and rock a show, you'd have to pay them for that as well. So, those 8's and 16's you desperately paid for will most likely never be performed.
But I respect the hustle side, the business side of it, the person getting that money, because if an artist can pull that off and bubble there reputation as "YOU NEED ME ON YOUR ALBUM TO SELL UNITS" and get some "lower calibre" artists to pay up for verses or choruses then good, do that. I'd do it if I had a name big enough for myself, but I would laugh at the artist paying me.