Neither Mössenböck nor Wirth were involved with the posted paper, and neither intended to create a "high-performance alternative to C++". The authors of the paper who made this claim are different people, who apparently didn't know C++ good enough.
The title of the article is quite clickbaity. Neither is the performance of Oberon-2 discussed nor how it compares to C++.
But you are wrong if you think that Oberon-2 wasn't considered a competitor to C++. I'd say 1997 was early enough that it wasn't obvious yet that Java would snatch up such a big part of C++'s market share.
Wirth has always been very critical of software bloat and C++ is an abomination in programming language design. They certainly didn't set out to make an alternative to C++ but a good language that was an improvement over Oberon.
C++ was never a role model, neither for Oberon nor for Oberon-2. Wirth was always opposed to C++ and Mössenböck worked in his group. The official goal for Oberon-2 was "to make object-oriented proramming easier without sacrifiicing the conceptual simplicity of Oberon" (from ETH INF Report 160, 1991). Wirth himself was involved when Apple designed Clascal and Object Pascal, and even though you see a different solution to OO in both Oberon and Oberon-2; the latter introduced the receiver syntax for its type-bound procedures, which you can also find in Go (not surprisingly since Mössenböck was the PhD supervisor of Griesemer).
