Help me understand the significance of EROI?

According to this guy, societal collapse is imminent because a. entropy and b. the high EROI (energy return on investment) afforded to society by the use of energy dense hydrocarbons such as coal and petroleum will decline dramatically in the near future due to the decreasing economic viability of acquiring them and the lack of a similarly high return alternative (barring nuclear fission, which is VeRy DaNgErOuS (and also practically infeasible politically in most countries that can achieve it), and nuclear fusion, which is, of course, perpetually 20 years away) and because this EROI is (according to him) what makes the complexity of modern civilization possible, it is inevitable that we will soon see a corresponding decline in said complexity (collapse). Now there is a section in the wikipedia article that touches on some of these points (Economic influence) so it's not totally junk science (if you trust Wikipedia, that is). However, I'm still struggling to grasp the significance of this figure. As long as our means of acquiring energy is scalable, why does it matter what the EROI is as long as it is greater than 1? if we need to spend one fifth of the energy we get from solar panels on making more, fixing existing ones, and installation, can't we just make a bunch of them to match our energy needs, even if they're growing? What am I missing here?