Yeah, I noticed that...is that why they stall minutes after appearing?
The DL periodically get money when played by the AI, which means, that they will never get broke.
The main reason for why the DL are so non-threatening is, that they need time to build up their infrastructure first. A lot of time, because the buildcost for the Industrial Sector is very high in the vanilla game.
The other two big reasons for why the DL are not as good as they should be are 1) their AI, and 2) their tech tree. Well, rather that their tech tree gets limited by what major races are in the game (just like it is for the minor races).