It's impossible for Lazio to win the title without even beating other top contenders. There are many title contenders in serie a and beating them all is a must for Lazio. The winner of serie a averagely needs around 90 points to take the title, wihch is hard to do without beating the big clubs. I know there's no knockout in the league. But, it's vital to farm three points from the big clubs. It stops other clubs from getting a chance at the title.
Lazio had already 3 defeats comparing to Inter for example which has only one. The draw could be related to a temporarily failure of the attack line but the defeat means that this failure touched also the defence line which might be more serious.
I don't feel that this version of Lazio could pick the league title but definitely the other teams in Serie A aren't any better since the difference between them is only one point.