All color paper was on Baryta until the mid 60s, and then the conversion to RC began. This was done in the interests of decreasing pollution and processing time. Baryta absorbs a huge amount of chemicals and this must be washed out.
The coating formula for many Baryta papers had to be adjusted with respect to RC due to the fact that Baryta absorbs chemicals from the emulsions and RC will not. Therefore, RC papers would keep better than the same formula on Baryta, and would be somewhat slower with the same formula.