abuse the substitution rules.

Never said anything about anyone abusing the rules.

"Big teams want it because they're selfish and there's no way it would benefit small teams"

What else explains the clear divide in those clubs for and against it?

Without that analysis it's just opinions on what you think

I don't profess to have done the analysis. The way to properly compare this would be to compare PL injuries this season vs. last season, Bundesliga injuries this and last season and then compare the two leagues. You can't just compare leagues this season because there are too many confounding variables, you need to know the relative injury rates between 3 and 5 subs for each league individually and then you can work out the impact of having two extra subs. You probably need to exclude tackles that were clearly from a bad challenge or the rare ones unrelated to football.

Use as many caps and bold font as you want, unless you're going to crunch the numbers you are also only presenting an opinion.