Something I noticed in the YouTube and Twitch streams is that players either manually retreat slowly all the way back to base to reinforce or they push forward with their weakened units whether because
a.) the base is too far
b.) They don't know how to reinforce
c.) What's Unit Preservation?
But I recall the Devs saying you could build bases all over the map to act as reinforcement points. And I have yet to see ANYONE do that.
I don't think the Devs even told their players that on/off stream. It seems like a lot of people disappointed that they can no longer retreat would be a bit happier if they knew that they could have constructed forward HQs so they dont have to walk all the way back or throw away wounded units to get new units.
You could also reinforce via Drop Pods too which I do think the community manager suggested to a player but he didn't follow up on that
I do think Relic needs to communicate better with the players at these events as I see a lot of people and YouTubers liking the game but lamenting the loss of the Retreat Function and the inability to reinforce on the battlefield. You can with the latter, but I don't think they know because it's not communicated with them.
This does bring up a question though... would building Forward Reinforcement Points be cheaper than pumping out all new units? I assume it would be cheaper and effective but I don't know as of yet.