[waheoo]

Messenger services live or die by network effects.

SaaS services with easily replicatable software live or die by building barrier to entry, usually this is done by building up a wall of feature add ons and integrations, in the case of Asana, integrate with all the things and suddenly it's a pain in the arse to replicate it all.

I would hazard a guess most the development effort is based around building up that wall of features.

[jariel]

Yes I agree. But my point with the Messengers is that it's not really 'scale' so much. Or dev ops. It's more likely the 'wall of features' and perception in business as being the Gartner 'Magic Quadrant' leader etc..