How I wish. Sure, for proprietary and commercial consumer-facing apps, it might be the case. There's a ton of proprietary/commercial development tools and infrastructure (hyper-optimized JVMs, k/kdb...) that are inverses of Wirth. FOSS has its opuses as well, but it's just as full of crap.
Amdahl's law only really makes sense in parallel computing.
Sure, but that doesn't mean one can just magic away blatant bottlenecks, and even if some speedup is possible, it does not retroactively make these decisions correct.
Contemporary computing is parallel computing. Even phones have multiple cores.