Not at all. If you've read and understood any of my posts on the subject you'd know that what the Democratic Party candidate needs to do is to motivate Democratic Party voters, and Democratic Party leaning independents to get out and vote Democrat.
If at the same time they can persuade moderate Republicans (if such unicorns still exist) to stay at home because the Democratic Party candidate isn't that scary and President Trump is a dumpster fire then so much the better - but that's a secondary concern.
Exactly the same thing was said about Jeremy Corbyn, and to be honest he had a much easier task given the Brexit mess, the Conservative leader and 10 years of austerity but he was an abject failure.
His outdated left-wing policies drove away support from the centre and right of the party. These people didn't vote Conservative but they also couldn't bring themselves to vote Labour. I did vote Labour, but solely as a tactical vote. It's the first time in over 30 years where I even doubted my vote.
Furthermore, Corbyn's policies and past political associations were far too easy to demonise which further motivated the right to get out and vote and caused some on the left to consider whether they really did want a return to the 1970's nationalisation and industrial strife (which isn't what Corbyn was proposing, but it was easy to frame it that way).