Microsoft has announced their intention to create an org-wide team for new small to medium tenants with under 5,000 users. This might help Teams, but it’s a horrible idea on many levels. Microsoft has no idea whether a new tenant wants to use Teams at all, so stuffing Teams down their throat doesn’t seem wise.
Org-wide teams are great because they feature automatic membership management. But sometimes you don’t want new Office 365 accounts showing up in org-wide teams. The solution is to create the account with some dummy details to mask the identity of the real person and update the account after they join the company.