Because the filter is doing its job. Something in the tank is producing contamination faster than a filter can hold it, and replacing filters treats the symptom while the source stays aboard.
The usual source is water — from condensation, a leaking deck fill, a poor seal or contaminated fuel — sitting at the bottom of the tank. Water supports microbial growth, and the sludge that growth produces is what blocks filters, along with degraded fuel and the rust and debris that lift off the tank floor when the boat moves. Filters block far more often in rough weather because that is when the sediment gets stirred up.
The fix works on the tank, not the filter: find and stop the water ingress, drain and remove water from the bottom of the tank, clean or polish the fuel, and inspect the tank interior where access allows. Serious contamination needs a proper tank clean, and a badly corroded tank may need replacement.
Once it is clean, keep it that way — keep tanks full to limit condensation, use a water-separating primary filter and drain it on a schedule, buy fuel from busy suppliers, and treat with a biocide only as directed after the water is gone. Biocide added to a wet tank kills growth but leaves the dead matter behind, which blocks filters on its own.