It doesn't necessarily matter whether they're still in use. All of these tools are worth learning, so that if a problem ever comes up that can be solved by markov chaining, you'll know it right away.
Same for all the other tools, though. And there are a lot of them.
What? That paper even says: Stochastic processes of the type described above are known mathematically as discrete Markoff processes and have been extensively studied in the literature; the corresponding footnote says "For a detailed treatment see M. Frechet ... 1938".