tldr; you can have do less goals, of course you can. They're just harder to manage than any of us expect them to be. That's why they're included with a premium plan rather than in the core.
No slur on intelligence intended. As far as I can tell, our users are some of the cleverest (and best looking) people. There genuinely are some ridiculously smart people on here. Do less goals are just harder to manage, even for people who've been beeminding for a while.
That in turn increases frustration and support burden, which is one reason that they're included in the infinibee subscription. So they exist, and work more or less as you might hope, but we try to protect newbees from the potential weirdness.
One of the problems is that if you stop reporting data for a do more goal, it'll eventually collide with the road and encourage you to update it. There's no such protection for do less goals, though we've tried a handful of mechanisms over the years.
Also, the concept of being 'in the red' on an emergency day is much harder with a do less goal, particularly given the variety of things that people beemind. Some goals are monotonic, others can claw their way back on the road, and for some even the concepts of road lanes isn't helpful for determining safety buffer.
And so many other quirks, some in the concept, some in the implementation, some in the mismatch between vision and reality.
PS: no need to have IFTTT scan your Twitter feed, Beeminder can do that directly, if it's a +1 you need. IFTTT could turn it into a -1 of course, which might work with a flat road and a do more goal.