Sam2
The problem is pretty oobvious, Chazal in Mishan and Gemorah were writting down the Mesorah, for the first time they were writing down the Torah Shel Ba’al Peh because of “Eis La’asos L’Hashem”.
Chazal foresaw the Golus and the fact that the MEsorah from Sinai would not be able to be maintained.
In order to ensure that the Torah Shel Ba’al Peh would not be forgotten in it’s entirety they had to write down everything and that included the “Esoteric” secret’s of the Torah.
However there are many things that simply cannot be written down for everybody, as such they had to be written in a way that those who were on the proper level would understand them whie those who were not on the proper level would not.
If you want a detaile dexplanation see the Ramchal in Mamar Al Haggodos where he expains this in detail.