First off, let me state that I am a BIAB brewer. Been that way since my very first batch. I use this method for one reason and one reason only: it's stupid simple. And I'm all about simplicity. If there are 5 ways to do something and all will achieve the same result, I will take the simplest path, which usually also has the added benefit of being the most cost effective.
When I first decided to try my hand at homebrewing, I did A LOT of research before I bought any equipment. Decided right off the bat that it was going to be AG from the start. Money wasn't really a limiting factor, but I also didn't want to spend more than I had to. I was all set to go traditional AG, and was in the process of finding a cooler on Craigslist to convert to an MLT, fretting over whether I should go braid or manifold. Then I stumbled across BIAB. Both methods achieve the same result using the same ingredients, but with BIAB the MT is my boil kettle and the LT can be wadded up into a ball and tossed into my BK for storage. I was living in a townhome at the time, so space was a premium. Advantage BIAB. Another advantage to BIAB is no worries about a stuck sparge. Ever. As a new brewer, this was one less thing I needed to be concerned about. When it came down to it, it was a no-brainer really. If I were going to be doing 10g batches, I could see going the MLT route, though BIAB is still viable, but for 5g batches, BIAB fits my needs perfectly. And with no pulley system or stepladder boom and no mess.
With the background out of the way, now on to OP's question:
I think some of it may have to do with the bizarre shroud of mystery surrounding AG brewing that it seems a lot of new brewers appear to harbor, which seems to be propagated by AG brewers for some reason. You see it in the "About to do my first AG batch" posts, as well as statements like, "I'm hoping to go AG someday, but for now, I'm resolved to brewing with extract" that are scattered all over this site. For some reason, a lot of new brewers are intimidated by the prospect of brewing AG, as if it's some kind of super-human feat. And it doesn't help when experienced brewers tell them to take baby steps by first doing a few extract brews to get their feet when, then graduate to steeping/PM, then after you've got all that mastered, go ahead and dive into the mysterious and complex world of AG. I kind of get it, but then again, I really don't. Like I said, AG is all I've ever known. My first batch was simple and easy and it only got easier from there.
So, with all of the above in mind, when one of these timid souls breaches the subject of possibly branching out into AG brewing, those of us who are enthusiastic about BIAB, knowing how stupid simple it is and realizing that we're dealing with potential delicate flowers, will enthusiastically lobby them to go BIAB so they too can share in AG nirvana without stressing over MLT's and fittings, and braid vs. manifold, etc. Let's not kid ourselves; anybody who is already doing AG knows how easy it is. For those contemplating AG for the first time, you can take two routes: 1) read a couple of books, watch some youtube vids, browse these forums for a while, then get after it; or 2) seek comfort, advice, handholding, and reassurance from other HBTers as to which path they should take to achieve AG. The former don't need our advice and will do whatever they think will work best for them. The latter, however, by the their very nature, need the simplest route possible. My personal opinion is that BIAB fits that bill perfectly, so when somebody comes asking, it's safe to assume we're dealing with a #2 personality and throwing a MLT project at them, while certainly doable, may not be the best fit, otherwise they probably would have already done it.
Sorry for the long post. Also, if I've offended anybody, I apologize. It certainly was not my intent.
:rockin:
