I use it - it is similar to Live View Boost.
I often use EV - 0.7 and if it is a dim room, the shadows are too dark to visually assess without.
If you are a fan of ETTR, your EVF will be artificially pale, so OVF is good.
If you are using studio flash for main light and M then your EVF will be too dark without SOVF.
If you want to visually assess the WB of mixed scene lighting, SOVF shows closer to actual
Different from LVB, the LCD will show image emulation, the EVF will show reality simulation