So Memogate is the saying that the Obama Administration relied on Steele's first
GOP then DNC/Clinton-funded opposition dossier (that is nonetheless fairly accurate) to green-light FISA applications to spy on Carter Page and the Trump Campaign.
Opposition dossiers are nothing new and not going away anytime soon. Carter Page left the campaign on September 26th, 2016. The surveillance began on October 21st, 2016, nearly a full month after he left the Trump campaign... but IMO there's no way they weren't tracking him sooner, considering Steele went to the FBI in early July.
The memo doesn't say what the results of that surveillance was, just that it was based on opposition research (kinda whiny IMO).
So... if you feel that Trump's collusion with Russia is fabricated (as many/most Conservatives proclaim) then this memo is
PROOF of Obama Administration/Clinton Foundation/DNC/Deep State using U.S. Intelligence against a political rival.
This is the reason Trump will fire Rosenstein and eventually Mueller.
On the other hand, if you feel that Trump has indeed been taking heavy Russian money since 2011 personally, then in his businesses (as affirmed by his own sons), and then throughout the Trump Campaign, then this memo is a nothingburger. There's plenty of smoke to justify those FISA approvals, with or without the dossier. #shrug