Do higher variance games produce higher winrates?

When I see graphs and winrates for the the best NLHE vs the best PLO heads up players the PLO players have far superior win rates compared to the NLHE heads up players.

I'm thinking one of the reasons is more mistakes likely in PLO heads up vs NLHE heads up, but the variance is still higher much higher in PLOHU vs NLHEHU.

Like its very standard to lose 10 or 20 BI in a single days play in omaha.

Also NLHE hu players require a much smaller bankroll than NLHE hu players due to the games variance.

But even when regs play regs in plo heads up the winrates for plo players are still higher and they are playing a higher variance game in plohu.