Having been a PhD student in his lab between 2005-2010, I can attest that's not true. Language design was definitely Martin's prerogative. As a PhD student, a lot of time went into implementation efforts, and while several features did end up in PhD theses, the last word on what goes in the language was Martin's.
Scala was ultimately a research project, with ambitions to succeed outside of academia. As such, some ideas worked better than others (pattern matching and case classes vs specialization). As it became clear that the language was picking up in the industry (lead by Twitter around 2008), many of these experiments moved into compiler plugins, macro libraries or research forks.
> Sorry, but Odersky is nothing like Wirth.
I haven't known Wirth to venture into such broad statements, but given what's been written about the way he lead his lab, I would say there were many similarities: a strong bias for solid implementation work, the (bootstrapping) compiler as a litmus test for features or performance work. And yes, a focus on simplicity.
Unfortunately, simplicity is often confused with familiarity. What's simpler: having statement and expressions as separate concepts that don't mix well, or only expressions? Most people coming from C and Java would have internalized the dichotomy and find it (or at least, back in the day, found it) "complex" to think of every expression having a type ('void' vs 'Unit'). The same goes for the split between primitive and reference types vs a unified type hierarchy.
This is not to say Scala doesn't have its warts, and implicits (in particular, implicit resolution rules) combined with macros could lead to a lot of pain. Hopefully there are lessons learned there and Scala 3 is better.
> Scala failed hard
Far from obvious. Databricks has probably upwards 10MLOC of Scala code, and seem to be doing very well (https://www.lihaoyi.com/post/TheDeathofHypeWhatsNextforScala...). Plenty other examples.
Could Scala have been more successful? Undoubtedly. But it's far from a "hard failure". New languages have adopted many Scala features, so nowadays Scala is believed to pay for itself only when using pure-FP libraries. That's very unfortunate if you ask me, since I believe there's a pragmatic sweet spot that lies around the style best illustrated by Haoyi Li's ecosystem of libraries.