My guess is It doesn’t really get better until obsidian. You will occasionally have a lineage dragon good enough to be useful on your roster, but since they don’t evolve it will be fleeting.
Currently I’m using sekoronos and Kelvin. Sek is almost done but he still has a few ounces of fight left in him (I got him 2 months ago ). Kelvin will be almost as good as my season drags for about 2 months until I hit sapphire evolve. Next month I’m breeding anapa and sekhem and I anticipate that they will be better than my season dragons for a month or so.
You get the idea. Lineage dragons not completely worthless but definitely not a major component of the game, except for breeding milestones to unlock the season dragon evolves.