Agreed. I do most of the above as an employee in a startup company, and we use Hubspot to have most of our marketing efforts "under one roof".

However if you're a bootstrapped company, you may not have a choice but to put the time in yourself rather than paying for professional SEO services.

If you have a technical and non-technical co-founders, this list is a large chunk of what the non-technical guy should/will be doing.

Building a great product that people want is pointless without letting people know about it.