for any product with extensibility and an SDK; during the Alpha/Beta/RC/Ship cycle the extensibility team needs to select a subset of the developer community due to the size of the community and the size the subset of the dev team that handles the incoming.
just to size this, back of the envelope, as an example: if the SDK team is 20 people ( 10% of the 200 ) then 2-4 of those are likely to be the customer facing and dealing with the external incoming as well as the internal "day job". how many ISVs can 2 people handle? 50? that seems like a lot but do-able. more than that, not likely.
the art and science of this is picking a representative subset of the dev community that will exercise all of the scope of the extensibility/SDK functionality to find issues.
so expecting "all developers" to be contacted is just a tad unreasonable.