Hmmm in the early eras you will see a lot of units that's true

If an empire has few cities, they will be filled with units. But if you play with multiple production on, and you designate one city to build nothing but elite troops, you should be able to amass a huge army in no time. I also suggest playing with unlimited wonders, so your troop factory can put a ton of great wonders to make troop production all the easier.
Another thing that helps is playing with field commander units on, 2 of these general units can help you conquer most cities, though it still might take a few turns. After you have two field commanders, you can add the other great generals to the city making your troops to increase their XP. Often this city will end up making units with 30 or even 50 starting XP by late game. Plus ton of starting religion and wonder promotions.
Also of note is the slavery civic. It will allow you to capture a ton of slaves. Add those slaves as citizens to your unit factory city, each one will give pernamant +1 hammer a turn. And with multiples from buildings, including heroic epic, this can easily equate to 4-5 hammers of unit production. In my current game I have 175 slaves added to my capital, it can produce over 10 units a turn, with about 30 XP each plus a few choice free promotions!

If thats not enough, I run civics to get +2 gold per specialist, which includes citizens. And I have every gold multiple wonder in that city, so I'm making over 7k gold a turn running at 100% science. Honestly I'm not even sure what to do with gold at this point.
This mod is easier than regular BTS for early warfare, where warfare was impracticle in early era due to lack of siege units before construction. Also the ranged bombard option really sweetens the deal. And overall this mod is joke in difficulty compared to BTS.