But did anybody claim that? The OP said "to handle spikes". That already tells it's an unusual solution for unusual problems by itself.
> Tesla uses local diesel generators to handle spikes.
This suggests that it is a standard solution for a reasonably common problem for Tesla. Common enough that it is seen as the accepted solution by the company.
The only instance I have ever seen of this was an attempt as anti-EV misinformation which was debunked. It is not a common solution at all.
It would definitely be a viable solution in some places and I am not against it, but for some reason the anti-EV lot want to push a narrative that it is common when it is not.