Archer:
Not all UFO reports are by lone witnesses. Additionally, the massive numbers of sightings, regardless of them being different incidents, still speaks to the reality of the phenomena on a wide scale. Certainly corroboration of individual sightings also provides more information for individual sightings as well.
Regarding your first sentence, the "event" is singular whether there is one or a host of "witnesses." Earlier I related how I saw a "UFO" that, thanks to binoculars, was determined to be 2 balloons tethered together. It's quite possible that more than one of my neighbors saw them sans binoculars so "multiple witnesses" to an event doesn't necessarily put ET in the driver's seat.
Your second sentence underscores what I already posted about the practice of lumping singular events together based on them being unidentified.
All UFOs aren't the same object.
Corroboration can help rule out fabrication in some instances and provide more information regarding the 'event' but that doesn't always help those peddling the ETH. The 1952 DC flap comes to mind. It's ETH angle certainly wasn't helped by the conflicting "information" provided by the various players. You'd have to allow for an "invasion" by the Federation of Planets (including denizens from the planet Invisible) to explain the supposed "extraterrestrial" UFOs that buzzed our nation's capital back then.
Also, "non critical acceptance" of the UFO phenomenon is not something that is supported by the evidence. Official and civilian investigators use methods to screen out a wide range of natural or manmade objects or phenomena before classing an object as a UFO. UFO reporting forms are proof of such screening. No responsible UFO investigator simply assumes that all objects described in the reports represent UFOs ( alien craft ).
I beg to differ.
You, based on the words you post, are an example of 'non-critical acceptance' and you're not alone. Regarding "screening" a UFO report, unless the "UFO" can be reproduced somehow (Campeche, Carter's Venus come to mind), it's just speculation and that varies depending on who does the "screening." There is also no foolproof way to screen for lies or delusion. I was never too sold on most post-mortem UFO "investigation anyway - the "thingie" is long gone and, outside of a few successful debunkings like my previous examples, we are always left with that pesky 'U.'
Lastly, it has been my experience that few people simply accept UFO reports at face value. There has always been an element of curiosity combined with a personal reservation or outright skepticism. I do however agree with the spirit of the comment in that blind faith is not something to base proof upon.
Well it's good to see we're not at logger-heads on
everything.

Just to clarify my POV, I'm skeptical regarding the ETH. FWIW I believe that a technologically advanced ETI is "out there" somewhere but need more than UFO reports to accept that they have been dickering around here for decades/centuries as some claim. It's a big universe and despite what some sci-fi programs show to make traveling to other stars a simple matter of "warping," the distance factor is formidable. That doesn't necessarily mean it's
impossible for hypothetical ETI to get here but it does make one wonder why, if 'they' come all this way, they just fart around doing stupid stuff like playing peek-a-boo year after year. I think it's much more likely that any given UFO is just something a lot closer to home that the observer can't identify for one reason or another. What I find telling is how the descriptions of "UFOs" often mimic contemporary expectations. We had chariots, wheels, shields, then "airships" that looked like blimps, "ghost rockets," and thanks to the media, "flying saucers."