I could mention that this site isn't the
only forum where RE projects can be discussed. I won't go into a pitch for some other forum (that would be in bad taste), but if you were to look around you'd find other fora that might suit your needs. Maybe you wanted to make a sales pitch for your CNC blades, or installation services. Well there's a place you can go for that; it's just not here.
Narrowing the focus on this forum wouldn't hurt, but a "DIY only" policy would have a few side-effects that must be considered:
a) Lower Google search ranking
Reducing the number of posts with recognizable, commercial, "searchable" names means that Fieldlines falls behind other sites that collect more keywords. Bow to the almighty "G".
b) Disgruntled members
It's a shame every time a member (whether they're new or not) get their postings zapped. Right or wrong, the person is discouraged. If they go away, then the eyeball count goes down. See part a).
c) Community
The information is usually what attacts people to the site. Whatever sense of community you get out of it is one of the things that helps them stay. Well, I'm speaking for myself, there. At some point you have to acknowledge that the variety of members' interests will include just about everything else under the sun (even politics, where the sun doesn't shine).
d) Cute dog pictures
If it's 100% DIY, then the pictures of the family dogs have to go. Plainly unacceptable!
Evolution of the site in the past couple of years has been very positive. All the time it's been a democratic process, so by listening and considering the feedback you will see the answer.
(PS Congrats, Tom, is this your first >50 character title?)