I really believe our lack of a true, long term, close, bitter rival is one reason why we’ve never grown bigger.
Those Cities / locations with 2 rival teams seem to embrace football a lot more leaving both clubs with bigger fanbases.
Sheffield, Bristol, Nottingham, Newcastle/Sunderland, Ipswich/Norwich, Pompey/Saints etc. plus the big city rivals. All areas where locals definitely support one or the other. Kids grow up one or the other. Weekends are all about the football and the rivalry. Family loyalty to 1 club. You want your lot to win, but also the hated rivals up the road to lose. The fans back their club completely against all comers. Siege mentality when things are going wrong. Not so much turning on themselves.
In Medway there simply isn’t that “us and them”. No early ritual where you support one or the other. No reason not to just support the bigger better teams up in the smoke. Fans berate their own club because they aren’t defending it against the loathed supporters of the rivals.
If a town like Maidstone, Chatham or Rochester, even a bit further afield like Ashford, Canterbury or such, had a long term decent EFL club that was a rival, I think both clubs would have a bigger and more loyal fanbase. The rest of Kent might also be more likely to go for one or the other of the 2 clubs in Kent.
As stevetreacle mentioned, 3x crowd figure when NMaidstone used to visit. It was similar for those 80’s cup ties.