Simple answer: 123 (34 members & 89 guests)

That's who's looking at the MR Deals forum right now. Those 34 members include me who wasn't there to do anything except check the stats. So cutting out the guests will reduce by 73% the non-member eyeballs looking at deals. During a hot deal, the number is probably much higher. A reduction of 73% will slow anything down.

Sure, people might post on Facebook (as I have) that you can fly NYC-MAD on IB-coded, AA-op flights, but that won't tell the common kettle enough to book it. They need to actually pore through the teeming posts on FT to get the details necessary to find available dates, date ranges, etc and book. That means signing up. Signing up means getting hooked. I'd occasionally see FT pages via Google before I was a member (never the MR Deals forum because no one searches Google for that kind of info--reference material is the kind of stuff Google eyeballs come for), but it was only after I became a member that I really got hooked and am now a useful contributor to the community. I would have likely signed up sooner if an FB friend had pointed me to an amazing MR Deal and had said, "You need to sign up to see it!"

So basically, the casual kettle whose friend tells about a smoking deal has two options:
1. Ignore the deal because they can't get the necessary info without signing up, prolonging the life of the deal. (We live in an ADD world as we all know by our legions of non-FT friends that don't take 30 minutes to sign up for 100k Chase BA jackpots.)
2. Sign up and have a very good chance of getting hooked and becoming a productive part of the FT community.

The purpose of this motion is to attract more members and slow the death of hot deals. This purpose is not to allow the open posting of $300 RTW FDs. We know that's not going to happen. The futility argument is a strawman. No-one expects that this will cause a certain kind of deal to be posted that is only shared one-on-one.