Let's check the etymology of "main":
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Old English mægen (Mercian megen) "power, bodily strength; force, violent effort; strength of mind or will; efficacy; supernatural power," from Proto-Germanic maginam "power" (source also of Old High German megin "strength, power, ability"), suffixed form of PIE root magh- "to be able, have power."
Original sense of "power" is preserved in phrase might and main. Also used in Middle English for "royal power or authority" (c. 1400), "military strength" (c. 1300), "application of force" (c. 1300). Meaning "chief or main part" (c. 1600) now is archaic or obsolete. Meaning "principal duct, pipe, or channel in a utility system" is first recorded 1727 in main drain.
https://www.etymonline.com/word/main
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Maybe it's an improvement. But not a big one (oh wait, 'big' is also 'power').