It's true that you can't really "buy" specific electrons from a micro-producer.* But providing a platform for the exchange can be beneficial, because it allows the producer to monetize their activity in a way that might not otherwise be possible, creating the financial incentives for them and others to (further) invest in creating more production capacity. Of course, for this to be useful the revenue obtained through the platform has to be higher than what you could get without it.
This is the same idea as Google and Facebook signing power purchase agreements with wind or solar farms. Goog/FB of course get their power from the grid and not a direct link to the wind/solar farm, but by creating the financial instrument of the PPA (typically at a higher than market price) they allow the producer to finance their project which can make the difference between it being built or not. It's a lot easier to finance a project when someone has committed to buy all your power at a fixed price for 20 years vs the uncertainty involved in the spot power market.
* this is true even at a conceptual level without getting into the physics of how electrons don't actually get transmitted from a power plant all the way to your house
This is the same idea as Google and Facebook signing power purchase agreements with wind or solar farms. Goog/FB of course get their power from the grid and not a direct link to the wind/solar farm, but by creating the financial instrument of the PPA (typically at a higher than market price) they allow the producer to finance their project which can make the difference between it being built or not. It's a lot easier to finance a project when someone has committed to buy all your power at a fixed price for 20 years vs the uncertainty involved in the spot power market.
* this is true even at a conceptual level without getting into the physics of how electrons don't actually get transmitted from a power plant all the way to your house