ps2 came out before the digital download revolution, was fully backwards compatible w/o any compromises and as we all know was a total commercial failure, right?

I'm not saying backwards compatibility is toxic, I'm just saying it's fairly useless (as far as making money is concerned).
But you have a point in that backwards compatibility helped the PS2 stand out from its rivals early on, increasing its install base who then in later years were ready to buy PS2 games.
However, because none of the competing consoles have backwards compaptibility this generation, I'd argue it's kind of a non-issue (again, if we're thinking from the moneygrabbing perspective).