this is not about who joined it earlier. since season 14 when economy was about to reach equilibrum. so since that season it became easy (or easier) to gather a strong team even for younger teams. it took while for them and now is the time they can compete with everybody regardless on when you joined the game becose for 10M now you can manage play-off easily. so now on every season will be equal chance for everybody who built up his arena.
what my point is - since season 14 the champions needed squad worth at least 1,2M (i believe it was more not sure though) on salary what is not sustuainable in game for more than season. even team that joined in season for ex.10 is capable of doing so for just 5 weeks. so keep it without salary cap but implement only 1 or 2 changes in team for a b3 season lets say out of week 3 (preliminary round could be done in week 1 or 2 where all the tanking previous champions and blank squad teams are eliminated and from that point you have to keep your squad at least for like 10 weeks..)
1 BBB, 23 Leagues, 11 Tournaments, 3 Europe Titles (SVK), 2 World Bronzes (SVK), 2 Europe Bronzes (SVK,FRA), 48 Seasons NT coaching