For the record, I disagree with the assessment that they should be building an Electron email client. Most users are already using a paid/monetised Electron email client, a soon to become Electron client (like is supposedly planned for Microsoft Outlook), or a webmail interface.

Electron clients cannot compete on deep technically obscure feature sets, simply because they didn't have 20 years to accumulate them. They cannot compete on latency. Thunderbird should remain native.