Democrats are playing a dangerous game if they avoid debates. A significant number of Dem leaning voters are clearly not satisfied with Biden. With no debates, these voters will not feel heard, and even if a miniscule fraction of them in the end break ranks and vote third party, that could indeed swing the election into Trump's favor.
Democrats need to welcome more perspectives. Make a bigger tent. Allow left and right wings of their party to engage in an open and public exchange of ideas. And hopefully find a new unifying synthesis.
A debate within the minds of dem leaning voters will happen regardless.
The more RFK Jr and Marianne Williamson get suppressed by the party power brokers, the better Cornel West does and more likely Trump will ultimately win.