I've tinkered with bikes and trikes all my life, and I experimented with ebikes over 10 years ago, well before they became as popular as they are now.
The early lead-acid battery bikes were untenable, with their short range and immense weight. If things had stayed the way they were, the market share would never have increased to encompass mainstream cyclists as it has now.
Lithium battery technology, sophisticated motors, and ultra lightweight frames has now given us everyday practical transport with electric power whilst still retaining some of the enjoyable healthy exercise element.
Yes, snobbery from many "pure" cyclists is still very prevalent, but sadly, bias and single-mindedness will always exist for many. I also enjoy riding
recumbent bikes and trikes, and they were banned from competitive cycling almost a century ago, because their reduction in wind-resistence wiped the floor with their drop handlebar mainstream competition.
As for some cycle shops denigrating ebikes or ebike kits, it's their loss.
If instead they accepted the rapidly increasing interest in assisted pedalling from their bread and butter customers, they'd claw back some of their losses to mail order.