I lurked this site for a while and I remember there being a much more present user base that all seems to have left. Probably just need more new members who actually feel the need to stay for more than a day or two.
Forums are becoming stale and obscure. Just like how nobody uses old-style phones anymore, that's how forums will become eventually.
Forums are taken over by other websites like Discord and other chat websites.
Many people here have grown older, leading to them growing out of this place as well as losing interest in SpongeBob. They're probably dealing with other things in life as well.
Going back to forums, Discord, phones, and the show, cable will likely become obscure as well, due to the video streaming sites becoming more common nowadays.
@ElectricPikachu True, but I see no need to worry. Old technologies and methods of communication hardly ever die off completely. Old rotary telephones, letters in the mail, hardbound books and human speech continue to function much as they had when they first arrived in the pages of history. I, for one, find a lot of charm in these so-called antiquated avenues of discourse, and I enjoy carrying them forward with others. I'm no luddite, but neither am I a believer in every new fad that crops up. There's a reason the older ways have stood the test of time.