Marketing without a solid product behind it is useless. I don't take any side here (definitely not Rolex's), but all these high end watch manufacturers had built up a reputation on good products because of the quality of their products. Customers are not all stupid milk-cows. If the product is not reliable and of low quality, it won't sell for more than a 100 years like Rolex or AP or Patek.
McDonalds has contributed to a global epidemic of malnutrition aided and abetted by invisible and unaccountable marketing consultants. Bloomingdales approved an ad campaign for its products that played on a date rape theme. The dairy industry would have you believe that it comprises small farmers working sustainably at a community level.
You're right that consumers are not milch cows. In marketing we use a slightly different bovine analogy: that of cows led over the grill, and funnelled into the abattoir single file. This applies more today than ever, with the rise of micro-marketing based on the data we leave strewn unprotected across the internet.
Watch brands are generally not as sophisticated as in other industries, such as oil and gas or commercial real estate. What they can do - and do - is trade on intangibles such as human sentiment. There are large margins here for manipulation.
Some brands are also capable of changing in order to preserve market positioning and status. You mentioned 100-year legacies. Well, in the late 1800s, Patek Philippe marketed itself for excellence in time keeping. It entered - and won - a series of observatories and chronometry trials. These wins were used to help profile the company for a certain type of excellence.
The quartz revolution killed all of that which is why today Patek Philippe doesn't enter into any impartial competitions on timekeeping. Neither do Rolex or Omega. The now-discontinued trials of the last decade were won by the likes of Breguet and Tissot. Patek Philippe and brands that try to emulate it have pivoted from performance to heritage. They haven't ditched performance altogether obviously, but its relative value to marketing is now diminished compared to the storytelling of heritage.
That's how the big brands survive: by changing the way they market, and changing the products behind it. They are also securing market dominance right now by upping investment in 'in-house' manufacture and
doing absolutely nothing to help suppliers and mid-sized brands cope with the pandemic. We'll come out of this with fewer brands commanding market share, and marketing that makes sure you don't pay any attention to any of this.