"However, in answer to your second point: Mountain Gorilla (unconfirmed until the beginning of the 19th century), Bili Ape AKA "Ngoloko"(2004 but known before that albeit not "scientifically" confirmed), Okapi, Vu Quag Ox, Laos Rock Rat, Komodo Dragon (1917), and Megamouth Shark (1971), to name a few I can readily recall. Most of these are larger than a bread box and are, indeed, of human size."
Mountain Gorilla ... first collected at the beginning of the 20th century. not the 19th, by essentially the first European explorer to enter their territory. No "cryptozoologists" involved. Also, gorillas in general had been known to science for over 50 years before that.
Laotian Rock Rat ... no history as a cryptid, found in a food market by someone who recognized there was something special about the little critter. In other words, pretty much the same story as the coelacanth. Note that within 10 years of the accidental discovery of the first specimen, we had video of a live one.
Okapi ... first sighted by Stanley in the 1870s (again, one of the first Western explorers to enter the territory). Specimens collected and classified in 1902. Specimen in zoo in 1918.
Vu Qang Ox ... again, well known to and hunted by the locals. No "cryptid" history. Described by zoologists shortly after their horns were brought to said zoologists attention in 1992. Not long after that, images of the living animal were published everywhere.
Komodo Dragon ... first brought to western attention in 1910. Described from a photo and skin in 1912. The first recorded expedition I could find that went to Komodo Island for the express purpose of obtaining specimens (1926) came back with 12 dead ones and 2 live ones.
Megamouth Shark ... completely unknown to science or even legend until the first one was discovered tangled in an anchor chain in 1976. Hard to be a "cryptid" when nobody even dreams you exist. Since the initial discovery, 41 specimens of what is presumed to be an extremely rare fish have been described to date.
Bili Ape ... seems to enter the literature in 1996. By 2006 DNA analysis had been done.
So, in summary, in the case of the Mountain Gorilla, Komodo Dragon, Okapi, and Bili Ape, not long after they were brought to western attention and someone went seriously looking for them, they found them. The Saola (Vu Quang Ox), Laotian Rock Rat, and Megamouth Shark were never cryptids to begin with, unless you want to claim that ANY undiscovered species is a cryptid.
In every case, no "cryptozoologists" were involved.
Now, by contrast, let's turn again to Bigfoot. How many years have people been looking for an animal which is supposedly distributed all across North America, and has been here long enough to have widespread native legends about it? 40 years? 50 years? That's a long time for little or no return, especially in contrast with your "cryptozoological success stories", which mostly involved people going to the area the reports came from, and coming back with a specimen,sometimes on the first try.