Disroot founder here 👋 if you have any questions I would be glad to answer. Been doogfooding all services myself as primary communication means. We are small team of ethusiasts and we mainly reuse code writtem by awesome FLOSS contributors in form of services. Not reinventing wheel here. Next year we will celebrate 10 years of existance \o/
You dont need to explain email so federation does not seem to be the issue here IMO. The problem is money which FLOSS projects usually don’t have. The successful ones have perhaps enough so that the devs can put food on their table, but not much else. Most of the apps are after Dayjob hobby projects. It’s hard to compete with those who have teams of paid staff.