It takes years after standardization for software encoders to become efficient, it was this way with x264, x265 and will again be the same with rav1e. Initially they're only going to provide a good quality/size tradeoff if you throw ungodly amount of CPU resources at them. There's also Intel's SVT-* encoder family, but that's meant for many-core server class machines, so again only good for batch encoding.

But for streaming services even those initially costly encoders are worth it since they pay the cost only once and then stream to millions of viewers.