Well It makes me smile rather wryly when Labour/Lib Dem/Guardian readers (I read it daily but have a different viewpoint) praise Rory Stewart as the best candidate as new Conservative leader!
If you asked Tory/Brexit Party/DM readers who the best person for the next Labour leader would be, they would probably say that nice Kate Hoey seems to have some sensible ideas!
Which is why it is right that only party members vote for their new leader - even in a scenario when that leader will also, by default, be the next PM.
After all, if the new PM cannot then command the confidence of a majority in the House of Commons, the rest of the electorate will soon get a say in any case.