E-bikes didn't exist for 100 years, and Velominati rules do not apply to e-bikers However, owning two e-bikes is very practical for me in the situation i have got rid of my car. There was a time when my big Vado was under total overhaul for 3 months but I could rode my Vado SL during that time.
The n+1 rule of cycling states that the number of bikes you should own is always one more than you have. This has been proven with over 100 years of data.
I would say the optimum is two very different e-bikes. Both ridden (alternately), both maintained.
Now: I've just watched a GCN programme where the guys rode vintage "mountain bikes" in the British winter gravel bike role. What they said was a modern MTB could not ride that fast as they were! Which reminds me formerly mine Giant Trance E+, a Trail e-MTB. I have never liked its performance outside off-road. I even decided I would not take it for a e-gravel race: too slow! Pity I didn't know that just 5 years ago.. A failed and expensive experiment.