I think the author hasn't researched the topic very well - there are a ton of startups who have tried this "stuff-sharing/selling model" and it hasn't really worked out.
Your post and outlook on this problem is the result of your definition of "sharing economy" being too narrowly focused.
To me it seems most people interested in the sharing economy only care about to talk about sharing if both sides of the transaction are individuals. If you're open to the idea that the sharing economy could be a transaction between a business and individual, then the market for temporary product rentals suddenly becomes a $40B space. This is nothing new, either. Small businesses have been renting out to other businesses and individuals since the 1950s. And, it's an existing $40B+ industry.
So while sure, peer to peer rentals for small items might never work, that's not to say that an "Uber for rentals" model wouldn't work. Uber started by bringing existing limo drivers online... not by trying to create a new supply side.
Edit: I also find the conclusion and only looking at drills to also be too narrow of a conclusion. Seems like most people when they look at tools only think about power drills. Totally agree that there isn't a $2B market for power drill rentals. However, there is a massive market for all other types of tool rentals.
I wrote a blog post about why a drill is a bad example for the sharing economy: https://www.credport.org/blog/12-Why-a-Drill-is-a-Bad-Exampl...