PPC could have any number of merits, the 2 nail in the coffin imho is that the community/implementations seems to have held on to a big-endian tradition whilst the mass of users/developers firmly shifted to little-endian when Apple went to x86 and that IBM didn't push it properly open in the 2005-2008 timeframe when PS3/Xbox360 were still relevant (OpenPower seems to have been created in 2013, after the creation of Risc-V and PS4/XboxOne going to x86).