To add to your reponse on MARKETING:
The company Tried and True markets a varnish made to a 19th century formula because it contains rosin. In varnishes rosin was\is considered an adulturant and creates little more than a cheap coating. Marketing.

While the raw materials change over time commerce doesn't. A good fixed oil varnish made with copal was more expensive than an cheap essential oil varnish with damar.

As much as things change they stay the same.