skepticism is healthy. i have plenty myself.
you joined blf two months ago, and maybe haven’t gotten to know folks in the community. (possibly you were a longtime reader before joining?) i joined about 18 months ago, and still consider myself new here.
but i’ve learned through reading his reviews and other posts that—to take just one example among many—if @MascaratumB publishes a review, it will be written by someone knowledgeable, experienced and honest, with humor and enthusiasm, and with patience and generosity in responding to comments and questions. it will include objective facts, opinion based on subjective taste noted as such, and a trustworthy assessment.
it’s a benefit to the community to get more flashlights into his hands, and into the hands of other member reviewers like him. that’s the goal here.
in the past, it was proposed to donate money and start a fund to purchase samples for blf reviewers. a good idea that hasn’t been followed through.
soliciting samples from manufacturers is another approach to the achieve the same purpose.
(if you have an alternative proposal for getting samples to reviewers, please share. keeping in mind that “buy with their own money” is already happening, but is a limiting factor for amateur hobbyists.)
is it possible that manufactures will send the best quality control samples? sure. but trusted blf reviewer will account for that. and in fact, sometimes reviewers do get dud samples, giving them an opportunity to test, and write about, customer service.
is it possible that the psychological bias in the studies you cited will occur? sure. maybe for the first few minutes of the several hours it takes to complete a review. again, just look at the evidence of the reviews on blf: can you recall reading one that smelled of shill?
an earlier conversation about this topic gets into the ethics of reviews. one interesting observations among many: @dave1010 writes about his positive review of a light that many considered a lemon. unable to get his sample to fail, he contemplated the impact to his credibility. well worth reading.