>>46507070Kanto got away with literally 1 dragon line. Pretty sure Johto only has 2 and one of them spends most of it's life as a pure water type first, and the other one is the 1 Kanto dragon line.
This trend was based for single player balancing and held true until Hoenn went full retard and added 2 dragon type lines and 3 dragon type legendaries in one fell swoop.
Curtailing it back to one (non-legend) dragon in the region and the legendary dragons that were allowed being all box legendaries was a good idea, but the damage was done and people expected Dragons to be available like regular Pokemon so after that Gen 5 went ahead and added 2 3 stage dragon-first lines, a dragon shitmon, and dragon legendaries. 3D gens continued with loads of low-power, easily accessible, 4-6 dragon types per gen.
tl;dr Sinnoh tried to curtail some retarded decisions gen 3 made but the damage was already done