It’s not only useful for very small teams. It’s standard tool for AAA games, especially open world games. You need lot of different foliage to create believable world.
Speedtree editor is designed for creating foliage. It’s lot faster to generate foliage using specialized workflow than reinventing wheel by doing everything manually in general purpose tools like Max. Usually you’re recreating real world foliage, so you want to use the same patterns for most of the games. And Speedtree utilizes these patterns.
Every decent engine supports Speedtree SDK which gives nice perfomance gain for foliage-specific meshes/materials.
I’m not artist and it’s very difficult for me to create even simple mesh in Max. Doing something like proper trees here is simply impossible without investing a lot of time to learn “traditional” modelling.
But it’s relatively easy to create foliage in Speedtree editor 