Basic economics sums up the problem very well. The only good comics are those that return emotional investment with interest (i.e. emotional payoffs, emotionally satisfactory conclusions, emotional highs and lows) and thus series which reliably make a decent return get a lot of people investing in them, and because limited and self contained series have a definitive beginning and end there is far less chance for the writer to fuck up and lose all that investment. However with ongoing series, this investment will inevitably be just straight up wiped out when the story and characters are made to radically change beyond recognition by exec/editorial order or the personal whim/autism of a new writer/writing team. When this happens repeatedly, investors all start pulling out and treat the property like its radioactive and will instead put their investment in more reliable properties. This is inevitable even if the entire writing team and every member of the company is nothing but nice and kind and tolerant and accepting of both readers as a whole and critical fans in particular. When the writers and company goons straight up declare everyone who withdraws investment a depraved rape-nazi manbaby and creates comics of them as caricatured subhuman neckbeard bigot scumbags well....withdrawing that investment becomes a whole lot easier.