You can easily offset its drawbacks and if nothing else, I would always play this over Progenitus
The Elf costs two, taps for mana of colors equal to your colors of mana, so three after you drop Loot
That said, Reyas just a 4/6 with no relevant abilities besides flying, it costs 9 mana in mono-white, and you need to reach your next upkeep just to get the ability
Path of Ancestry Typal decks just want to keep their creature of choice flowing
If you are mostly tokens and enchantments then Mother is poor while if you have all the Blood Artist dudes or the prowess token generators Mother will be yet another must kill cheap dork and will absolutely steal some games
As the most popular Commander from MTG Avatar, it seems players cant get enough of this cards spell-doubling shenanigans