nobody could know exactly is a family is viable or not, your only sources are the indictments but they are not enough it depends on the place...
according to your logic the mafia in the 60s was weaker than today because the lack of indictments of that time?
there are several factors, the indcitments and you're right, but you have to consider other factors like the level of corruption of a specific area
if buffalo is more corrupt than detroit for example you get a lack of the ones in buffalo