Do you think a 100W SSB commercial rig is a serious one? If yes, let's see why D4D is serious as well.
Human ears can hear 6dB-10dB Signal to Noise Ratio when we do SSB QSO. However, FT8 can decode -24dB SNR. It is at least 30dB difference and it will translate to 100W vs. 0.1W. Now D4D can transmit 1W and only half of it will be effective, so it is 0.5W FT8 and it translates to 500W SSB. So, do you think a 500W SSB rig a serious one? It explains why over 9000km QSO can be achieved.