a lot to unpack, bear with me
first of all, @everyone, "reasonable spread" is a glossary term in the current ranking criteria, so please go read up on that bc it makes a lot of things more clear, like how single diff sets innately feature reasonable spreads
"single diff mapsets wouldnt feel like mapsets"
people are already well accustomed to single diff mapsets because marathon sets get ranked like every day, there will be no difference. its not like the average really think "mapset = a set of maps" anyway, they just play diffs they find, no reason to bar this from passing because of a weird pseudo-technicality
"i could make just a 1 minute normal and rank it"
yeah and you can make a 1 minute EN set right now and rank that, there's basically 0 difference in effort or value. 2diff requirement doesn't keep people from making stupid sets, and it doesn't even discourage it. changing this to a single diff requirement will not encourage it any further because people don't really like to make stupid sets anyway, or else we'd see a lot more of them rn
"it defeats the point of having spreads to begin with"
again, marathons are already very prolific and are not inhibiting spreads in any way. tv sizes are super popular and always will be and will require a full spread, 3:30 H sets will not intrude upon that
"it promotes laziness"
it also promotes caring about the single difficulty you want to make instead of phoning in a forced difficulty you don't want to make. people are always going to be lazy but at worst we get 1 lazily made difficulty, which surely is better than 2
"2 diffs promotes variety/appeals to more players"
except EE/NN/HH/II are all rankable and do not promote either of those things. in fact of all the listed sets the ones we have ranked right now are EE and NN....
mir did a good job covering a lot of arguments already, was there anything else? i may have missed something..
basically by removing the 2diff requirement it makes for overall more clarity when the proposal goes through as all you need to understand is "linear spread from this diff onwards." forcing II sets in 4:30 songs is very awkward and unwarranted as it does not promote good content but instead just arbitrarily forces more content. from what i can see there is no benefit whatsoever from requiring 2 diffs
@doormat your concern about the bn rule interacting poorly with single-diff sets is valid, but that seems more of an issue with the bn rule itself, which is a very different topic. we shouldn't let bn rules interfere with improving ranking criteria.