system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] Why houses that have few thousands of soldiers and a hundred ships at best are presented as particularly powerful and influential in the galaxy?

Tywin Lannister (Game of Thrones) alone had 30 000 soldiers in his army. Clone army (Star Wars) had more than a milion

Small scale in Dune is especially visible in the main battle, visuals are great but it still looks like local skirmish more than battle of ruling houses of the empire. So to the actual question - is it because of the limitations of the genre and movie technology, or is there watsonian explanation based on lore?
gpt
FTL travel is monopolized by the Spacing Guild. Cargo space for soldiers and attack craft on a highliner is extremely costly. The Guild itself also has an interest in limiting the scope of conflicts on Arrakis so the spice will continue to flow regardless of who wins the fight. They don't want the mining equipment damaged by an unrestrained conflict.