True - for some! Others can be very finicky and flower prematurely giving very low yields. But, for me, it really boils down to this...
Take any strain, Jack Herrer for example. If given the choice to run JH auto or photo I'd take photo EVERY time. How can the strain be improved by crossing with Ruderalis (other than passing on the autoflower trait or maybe some more vigor)?
IMHO, crossing with Ruderalis "waters down" the genetics which is the sacrafice you pay for the autoflower trait.
My view is slightly different. The introduction of a more diversified cannabinoid and terpene profile is worth it.