@Rich35
When I started out as newbie without any reviews I was able to send reference invites by emails to all my friends and family who had over the years stayed with me. But now it's only thru Facebook. I'm thinking that what you're experiencing is a temporary glitch.
It's true as @Gerry-And-Rashid0 say, references aren't as valuable as reviews, and references also disappear further and further down as new reviews appear.
However in my experience several of my first guests remarked on my "good reviews" because they didn't know the difference.
And when I see how esp. newbie hosts are targeted by all kinds of bad guests who wouldn't have a chance with experienced ones, I think that having a number of references can give your listing less of a newbie look.
You didn't hear this from me, but you could do the following: invite family or friends to book maybe for a night, even at the lowest amount Airbnb allows in exchange for a review. Reimburse them every $ they paid to Airbnb, and it's a small investment for some good reviews.