So, with all the modern technology, they haven’t come up with a better solution. The polysulfide works well and is repairable. The airlines still use tons of the stuff. The more modern polyurethane sealer, has the Navy in a pickle. They have a bunch of planes that they cannot service because they cannot strip this stuff off the airframes.
It reminds of a talk at the Aviation Maintenance Seminar about 5 years ago about fuel tank bladders. They said in WWII they designed bladders and they saved many lives. They were made from cotton reinforced rubber. In the 70, they thought they would improve the bladders by using the more modern polyurethane. After about 10 years in service, the fittings started falling off. Nowadays almost all bladders are made of the more reliable cotton reinforced rubber.
FWIW, polysulfide is widely used these days. It is used to seal expansion joints in concrete and to seal windows in buildings. In most cases it is considered the superior sealant