I understand that Hubspot comes at CRM from the perspective of marketing automation, but if serious about competing here any holes in basic CRM functionality puts you at a disadvantage. This is a big one, particularly when attempting to leverage partner integrations that expect aCompany to be joined to each Deal/Opportunity.
I agree with @GLR that you can’t expect busy reps to comply with “optional” data entry, nor busy managers to chase after bad data.