You forgive Everlane because you like their emails.
If many of Weebly's actual signups have a reaction similar to your Everlane reaction, something like "NEATO I'D FORGOTTEN I WANTED TO GET MY WEBSITE UP WITH THAT BENEFIT", then what's the problem?
I guess I'd ask the question like this: is there no room for taste [1] when it comes to emails?
We can all agree that different audiences will find a particular email more or less engaging. The same way we might say "mathematics is beautiful", is there any room for saying "that marketing campaign" or "the way they engaged with their customers" is elegant?
It's worth remembering that the Weebly emails were sent more frequently then the Everlane ones. An email every month or so? Ok, not a problem. An email every day for more then a week? Back off.
Email volume does matter. You can send too many emails and annoy your users.
If many of Weebly's actual signups have a reaction similar to your Everlane reaction, something like "NEATO I'D FORGOTTEN I WANTED TO GET MY WEBSITE UP WITH THAT BENEFIT", then what's the problem?