I never said build the whole CMS/store platform from scratch. I would use something like Perch which is a CMS with shop-addon that allows you to build the site and store normally, then integrate easily into a shop. It's possible to be up and running quickly using a basic shared hosted platform as the host - which is all you need at first.
The day that "scaling" is needed is the day you ask your web host to put your mySQL e-store site on a better shared hosting plan with more RAM and more CPU... wow, what a huge effort! Or go VPS or something. Easy.
Every used mySqL? It actually works quite well believe it or not. Cheap, easy, not a headache.
We can argue all day about the details, but in the end you are advocating a microwave dinner as the solution for a small business wanting to make an impact and good impression with new customers. I am advocating something a lot better.
Some small businesses are looking to set up shop properly more than quickly. Anyway, these are all opinions, I'm just sharing mine.