I've done a lot of reading about merging these past two days and I feel like I can give it a better shot (I dont think my previous attempt at merging went perfectly well..

)
Though I do have a really simple question that I cant understand...
Why must we merge mods in Gecko?!?!
As an example.. (Purely hypothetical, but very relevant)
Lets say I have a UL which revamps a specific area, and I also have a mod which dumps the entrence to a cave there. The mods arent compatible, and the cave is now floating 6 foot off of the floor. So I get a patch for it. All this patch does is raise the ground to the caves level, so it is no longer floating.
What is stopping me from opening the TESCS, loading Oblivion.esm, the UL.esp and the patch.esp and setting the UL.esp as my active file. Cant I
litteraly just save the .esp now? Making UL.esp have a raised floor in the first place, and then just delete the patch??
In my mind that should work for all kinds of things.
A real example would be with 'Let there be darkness'. I have to use an extra .esp ''Mehrunes Razor compatibility'' with it since I use that official DLC. Whats stopping me loading Oblivion.esm, Let there be darkness, Mehrunes Razor and the compatibility patch into the CS and then save. Could I now get rid of all of them except Oblivion.esm and Let there be darkness?
Why not?