That's what I like about my FrSky Taranis.....you can buy their receivers and use their system/firmware or plug in other modules and use your existing receivers, I'll use Spektrum as an example in this case.
Let's say a person has 15 airplanes and is currently using their favorite brand X radio, so that's one radio and heavily invested in 15 receivers. Then a cool new radio comes out, the big dilemma is.....will they be willing to reinvest an average of say $110 per receiver, depending on number of channels needed, that comes to $1650.00 plus the cost of the radio. The average person is going to take a look at those numbers and probably determine that it's not a very realistic investment.
With an open source radio and being able to use your existing receivers, it will be easier for the average person to swallow the investment in just the cool new radio.