This problem could be solved if we fixed our tech access and intellectual property laws. The constricting elements of the online network effect only exist because we have laws that grant artificial monopolies. The only reason that Discord and/or Slack and/or OtherAlternative can't make it seamless is because Microsoft/Skype would likely file a lawsuit. While there are hairy intellectual property issues at play here, MS's best vein of attack would be the CFAA, which would almost certainly criminalize something like Slack connecting to Skype's network to offer an adapter/bridge between the two networks.

People comment on the queer nature of this phenomenon frequently but seemingly fail to understand that it's that way because We The People made up laws dictating that it should be that way. There is no deprivation of either possession or use of property here, so why did we make this illegal? Let's fix the problem and allow true competition, instead of protecting lumbering incumbents.