Thanks a lot Bartosz, interesting question.
I think a good way to separate these two aspects you are mentioning is to distinguish between low-touch SaaS and high-touch SaaS. I think the “typical journey” from SMB to Enterprise is just stronger in our head since we haven’t spent much time working in Enterprises ourselves and are used to many low touch SaaS products we use on a daily basis such as Slack. But targeting Enterprises from the beginning is just another way of building a company and looking at it — and there might be actually less competition compared to low touch SaaS models today. In this perspective I like this article because it gives a good overview about it: http://chaotic-flow.com/saas-startup-strategy-three-saas-sales-models
One of my finding was — and I don’t know the exact reasons for it— that especially German startups targeted enterprises from the beginning, bootstraped for a couple of years and then raised a big growth round.
P.S. At the moment we’re not planning to open source the doc, also because things change (further funding rounds, acquisitions, etc.).