Bitcoin's dominance would be probably close to 100% if we were to exclude all the useless shitcoins and tokens from these crypto rankings lists. I'm personally not concerned at all about the % calculated anywhere - whatever happens, we all know BTC is almost always needed in the end.
This is too extreme, marketcap is mostly using for comparing coins, even though it's not a good metric, so what's the point of disqualifying all altcoins if there's no one to compare with then.
The site mentioned in article uses good methodoloy - it excluded stablecoins, tokens, non-currency projects, so that Bitcoin can be compared with coins that are trying to be its competitors. Bcash and BSV are scammy shitcoins, but for the sake of argument we cam compare their marketcaps to Bitcoin's, in order to draw some conclusions.