The EPL hasn't actually had, in the majority of seasons, a huge number of clubs who had a realistic chance of winning. 3, maybe 4, in most years. Out of curiosity, I had a look at La Liga and the Bundesliga as a couple of examples. It would appear that since 1984/85 one of two clubs has won La Liga every year except on 5 occasions. In the Bundesliga, apart from 8 occasions, one of two clubs has won it every season since 1984/85. So, although it's not as spectacular a domination as it is in Scotland, it does show that 2 clubs dominating domestic football in a country isn't confined to the SPFL, although the gap between the "haves" and the "have nots" in Scotland is wider.
Some if us just get on with supporting Scottish teams other than 'The Ugly Sisters'. :-)