It’s still a valid strategy and it makes sense in the current economic system.

It's not really tenable because it just takes someone without a profit motive to reimplement it or something that can substitute for it and the business model breaks. There's countless examples of this.

Any product that requires many years of R&D has to rely on trade secrets or on software patents, since otherwise the company could not possibly compete with copycats who reverse engineer their know how and therefore have zero R&D costs. There is often no other way, not every market is based on constant fake innovation and feature creep.