I've never had a proper "blood economy" going in a MP game - I don't think I've summoned a single blood based critter, in fact.
I do find that blood is worth while to search for; even if it feels like "wasting" an expensive B1 mage (Vanheim and Pangaea's 280+ options come to mind) to blood search, it can be worthwhile just for the items that can be forged; single handed life stealing weapons and magic skill level raising items come to mind.
As Norfleet says - it can be difficult to get into the semi-finals in a game with experienced players without either blood or death. I confess I have much more experience with death, so my opinions on blood should be taken with a little ... salt and blood.
They both have huge advantages in some ways. Blood isn't reliant on finding magic sites - only population, thus isn't affected by site settings on a game, nor luck. On the other paw, death isn't reliant on micromanagement, and imo is more generally useful - that opinion may be tainted by my preferences in the game though, a lot of CW especially, and some other themes with death scales added (Helheim Vanheim, etc) and not so many games with the proper blood nations.
But - if you're not going all out blood (as in, heavy blood research and relying on blood summons) then it seems you don't need to get the blood going all that soon. My reasoning being that the blood does you no good unless you're going either heavily for blood or construction research.
If you're going for construction to use blood,
and don't have any reasonably priced blood hunters, it's better to wait until you're near the construction level you need to capitalize. Scrounge up 5 or 10 or 20 slaves just as you get near to constructing sanguine searching sticks and use the SSS. A single blood 1 mage with a stick can garner far more than you would get from most magic sites - I've seen B1 or B2's (not sure which) with SSS get over 10 in a turn.
That makes it fairly easy to bring in forging incomes, if not summoning incomes.