Everyone adopted Istio because everyone else was adopting Istio. Complex, resource-hungry, and solving problems most teams didn't have — it was the poster child for resume-driven development.
Service Fabric got a lot right — stateful services, the actor model, rolling upgrades with health checks. But it lost the ecosystem war to Kubernetes, and being technically superior wasn't enough to save it.
We were using FluxCD to reconcile Kubernetes state from git before anyone called it GitOps. The tooling was raw, the wins were real, and the company that coined the term went bankrupt. Make of that what you will.
The cloud wars are raging. The secret to coming out unscathed is to back open technologies, think carefully about IaaS vs PaaS, and not get locked in while the giants fight it out.