Do the email client still default to TXT nowadays ?

Regardless how basic the email, it seems Outlook, Hotmail, Gmail always send them in HTML and I need to do something special to send it in plain text.

At work, the mail very often have some sort of minor formatting. A bold sentence here, a reply in a different colour there, or even simply links. Except for automated alert message from a system or another, the emails are basically always HTML.