Bloodlines counts towards ECL by RAW!

[HouseRules]

It does not matter that bloodline is relatively useless. It is useful because they count as Hit Dice (while not giving any actual hit die, but counts towards skill cap), and Caster Level to all Spellcaster Classes, and anything else scale-able by level.

Even if bloodline is relatively useless, Mundane is also relatively useless. If you say one, why not the other?

Edit: Old School has a term for ECL: Adjusted Hit Dice. Yeah, the concept that casters are stronger than Mundane requires monster's Hit Dice to be adjusted for the calculation of experience.