I could say the same thing if I saw Motorola contents in a Galaxy casing: "Oh, its harmless. Its not like they are achieving anything"
It wasn't developers that introduced this idea; it was a console competitor -- one that is struggling at the moment to keep up.
That is not accurate though.
Fact check it yourself if you don't think it's accurate..
1) MS has been against Crossplatform play for the most part since forever; even losing games altogether over their stubborn stance. Sony always maintained that it's in their DNA to support Crossplatform play and that has been the way it was for the most part for all kinds of titles.
2) In Dec. 2015/Jan 2016, Rocket League developer announced their game for XBO, without crossplatform play because MS shot down the idea from the start
3) Internet has a s*** storm about MS's stupid policy on Crossplatform play, how can they be so dumb. Nobody favors the lack of crossplatform play because you lose braincells when you argue against something in favor of shareholder ideas instead of things that purely benefit gamers. This put heavy pressure on MS and Psyonix took advantage of the situation and started talks with MS.
4) Three months later, Psyonix announces XBO has crossplatform play with PC and soon PS4 when they have everything finished. MS announces they are opening everything up for crossplatform play, ios/android/PC/anything...
5) A little bit later, Psyonix updates and says Sony isn't playing ball. They mention they have 100% technological solution literally a button push away to implement crossplay for PC/PS4/XBO.
6) Sony makes a statement saying they are always open to crossplatform play and you need not worry... then completely ignores it for the next year; no progress or talks according to Psyonix (also no internal dialogue according to Sony). Rocket League comes out and is patched with crossplatform play on XBO/PC-only, just like they said.
.........................................
That is an accurate summation, feel free to correct me but I don't think I missed anything.
-By that timeline you see that MS was completely against it until social media, press and Psyonix hammered the point home to MS to get in line. Psyonix is the catalyst for MS changing their stance on crossplatform play. Even Wargaming, a major partner of MS's since 360 days, could not get them to budge on that policy.
-Is it MS's fault that Sony was being completely full of s*** in saying that they welcome Crossplatform Play? Should MS have kept their head in the sand on crossplay and continued to look like morons while Sony is openly saying it's something they support and coming off looking like the coolest kid you've ever seen?
Now at the moment, Psyonix is still sitting on that button and Sony has readily admitted that they basically never had any intention of doing crossplatform play with XBO, even though Sony intentionally misled press and gamers that they would.
While the world was waiting on Sony's response, more games got stacked on that list, waiting for Sony to commit either way.
Anyways, back to your post... MS adding Sony users to their reports is simply a crackpot theory. No basis in reality. You are literally making things up to try and justify this from a shareholders perspective.
Rocket League on PS4 has cross play though.
It works out to be PS4/PC OR XBO/PC; which is silly.
The developer wants PS4/PC/XBO, everybody swimming in the same pool.