Blending scenes between presets requires that all blocks in each scene be added into the destination preset, in the same order in the layout, and the channels in each block be enabled or bypassed correctly, and the parameters adjusted accordingly to the channel’s settings.
Look at two similar presets. If the blocks vary in their order the software could not determine how you wanted them to be arranged when it was done, but we know it wouldn’t sound right. If two of the same blocks existed, what is the software to do with channels that are conflicting?
The software can’t make those decisions with any sort of reasonable success rate. And what will people do when it fails?
It requires us to analyze the presets, find the commonalities in the blocks, then dive in and find how each channel is used, then begin combining them together. It’s a tough enough thing for us to do, it’s not something that software can do with any sort of reliability.