https://sh.itjust.works/post/27122034

I blame the gay panic of the 18th and 19th centuries.

Broadly, and without evidence:

Women in formal situations were decoration, another piece of fashion attached to a man.

Edit: https://en.m.wikipedia.org/wiki/Great_Male_Renunciation

https://youtu.be/uAKMolRKphE?si=T7SS0saI_GFQtdrj

Derek Guy breaks it down some in this podcast. But it was a shift in the house of commons in England as it was working Man's clothing and was a way to signal you were with the people and not aristocracy.

Beau Brummel's influence is the reason, though he would have detested the uniformity of it all.

https://en.m.wikipedia.org/wiki/Beau_Brummell

A good Behind the Bastards on him: https://open.spotify.com/episode/00n2CANk00e5P2L0H348h1?si=1VhgCCRnQQueiPBFSfjJLg

where the only acceptable style is jacket with pants?

Well, there's the Scottish, who can do a gussied-up kilt.

https://en.wikipedia.org/wiki/Highland_dress

Formal evening wear (white tie)

The traditional white-tie version of Highland dress consists of:

Men:

• Formal kilt doublet in barathea or velvet. The regulation, Montrose, Sheriffmuir and Kenmore doublets are suitable in a variety of colours. Velvet is considered to be a more formal material. The Prince Charlie jacket (coatee) is considered to be less formal,[by whom?] although when introduced it was to be worn with a white lace jabot. Tartan jackets are also seen.

• Waistcoat in white marcella, tartan (usually to match the kilt), red or the same material as the doublet. No waistcoat is worn with the Kenmore or Montrose doublets.

• Kilt with formal kilt pin

• White stiff-front shirt with wing collar and white, gold, or silver studs and cufflinks for the Regulation doublet, or a white formal shirt and optional lace cuffs for the Montrose, Sheriffmuir, and Kenmore doublets

• White lace jabot. A black silk or a white marcella bow tie may be worn in place of the jabot with the regulation doublet (Highland wear often includes a black bow tie even at white-tie events).

• Black formal shoes or black buckle brogues

• Tartan or diced kilt hose

• Silk garter flashes or garter ties

• Silver-mounted sporran in fur, sealskin or hair with a silver chain belt

• Black, silver-mounted and jeweled sgian-dubh

• Highland bonnet (Balmoral or Glengarry) with crest badge (only worn outdoors)

• Short belted plaid with silver plaid brooch (optional)

• Scottish dirk (optional)