Let's say you want to start with a fully loaded Asus B250 Mining Expert rig (19 GPUs), would there be a point for solo-mining?
Simple answer for most coins, No.
FYI: For starters you would never be able to fully load an Asus B250 with the same brand cards, you would have AMD and Nvidia cards mining two different algorithms. You can't get 19 AMD or NVidia's to work on that board. I just returned two of those boards after only getting 12 or 13 NVidia's to work. Not enough PCI-e lanes to be reliable past 12 cards, better to stick with the Gigabyte B250 with 12 slots. No sense in having NVidia and AMD on the same MB anyways, opens a can of worms.