Unfortunately, this is false. The FDA will still intervene in situations where it doesn't like what you're doing even if you don't advertise your work as a drug, medical procedure, or as having any particular efficacy.
https://www.technologyreview.com/s/603530/a-biohackers-plan-...
On another note, see the sensor pads story here: http://www.fdareview.org/devices.shtml
"We rarely get to try products that the FDA fails to approve, and we never get to try products that are never brought into existence because FDA rules and regulations have made research and development uneconomic. As a result, the public remains ignorant of the true costs of FDA power."
But yes, the FDA aren't complete morons. If you're selling genetically modified dogs you're obviously selling the results of an unapproved medical procedure to the public, even if all you say about it is that you're selling fluffy friends to the public.
The second story you've linked to is one where someone was clearly trying to sell a replacement for breast examinations to the public.
I've never heard about the "sensor pad" before, and there's probably a good case to me made for such a device being more beneficial than not, and that the FDA made a mistake etc.
But I think their process is more sound than not in demanding clinical trials of these sorts of products. This is because in practice people will use them as a replacement for going to their physician, so having some DYI breast cancer scanning kit doesn't just need to be harmless in isolation. You also need to consider the increased death rate from people not going to their doctor for an examination as a result.
This is completely false. Proof: homeopathy and chiropractic are very popular and still on the market.
Nothing is stopping decentralized decision making, you just need to market whatever non-effective but safe remedy you're selling as a food supplement, a tea or whatever. You just can't advertise that it's a drug.