I'm not sure I agree with the premise. The corporation's popularity spread with the growth of railroads: large undertakings, needing lots of investors, operating over large areas, usually with some years before any dividends would accrue—and most importantly, whose operations were inherently dangerous. Investors naturally sought to be shielded from personal liability for wrongs done by some remote employee.

Trusts arose much later, as a way to get around the early restrictions on corporations. State laws often did not allow corporations to own stock in other companies, to operate in more than one state, or to undertake activities (such as owning an office building not entirely for their own use) even slightly peripheral to the powers enumerated in their charters.

when all of the great gilded age companies were organized as "trusts?"

This is a misunderstanding. The trusts were mechanisms to consolidate and streamline control of the vast web of corporations that made up the great "Gilded Age" business empires, they weren't the operating businesses themselves.

For example the first such 19th century business trust was established by Standard Oil in 1882, in which the individual shareholders of the many separate Standard Oil corporations agreed to convey their shares to the trust. The trust was governed by a board of 9 trustees, with John D. Rockefeller owning 41% of the trust's certificates.

You can see how this makes governing the corporate empire much easier than having to deal with the individual stock and governance of each corporate entity separately.