I personally think that the thorns crusader is one of the most refreshing things we've ever had, because it's the first spec in the history of D3 (to my knowledge) that is a DPS spec but doesn't rely on stacking CHC+CHD :-)
What makes this thread "stupid" is that you only deal damage every 12 seconds for 4 seconds, but that's not an issue of the LoN Bombardment Crusader, but it's rather an issue with CoE (otherwise the bombardments from belt would be a significant part of your damage and would make it much more interactive and less "cycle-oriented). So don't blame the spec, blame the ring!
In terms of comparing damage, nothing comes even remotely close. Without having tested it this season, I'd say it's probably LoN bomb >> Invoker > Seeker of Light/Akkhan builds > Roland's (though that last part is more or less guessing, no one's really tested them for hundreds of hours, and it takes thousands of hours before a build really starts to shine on the leaderboards).
The core issue that the crusader always had is that you need to make great trade-offs between survivability and damage. For example, the crusader has the strongest damage buff in the game (Law of Valor - Critical); but using that makes you super squishy as you give up on all the defensive laws. Plus, not many builds have 100% Law uptime, which is unfortunate and even unfair given that many other classes can have permanent uptime on much more powerful skills. Again, the thorns crusader shines here because it doesn't need to make that trade-off (great defense since you don't need CHC/CHD on gear, and Critical is useless as well). It's an artifact of the initial design philosophy of the crusader as a "medium ranged class".
Two other issues are that the crusader has never been "the strongest class" in any season, and wasn't a vanilla class. That means it didn't have any "champions", i.e., famous streamers focusing on it for 5 years, and also not the millions of players switching to that class because it's the "flavor of the season". DH wasn't the most popular class in D3V by any means, but since DH dominated S1-3 it has a strong loyal fanbase and therefore more access to theorycrafting. The only player who really ever did a lot of in-depth theorycrafting on crusaders and showed long-term commitment was MannerCookie... who was banned and left the game. What that means is there's no one driving the class theorycrafting for crusaders, and not a strong number of players pushing the class; and since it became really bad solo in season 4 and isn't part of the group meta for half a year now, there's very little testing.
And i am a huuge huuuuge fan of Crusader. I played the shits out of him when i bought ROS.
And crusader was "good" only once, with the FOTF build in t6 rifts.
Never DPS since then. Never welcomed in groups. Never in greater rifts as DPS. What a shame. Class has so much diversity and so much potential. Many items. But still so many flaws and ALWAYS outperformed by other classes. FeelsBadMan
that firestarter rune nerf was HUGE, blizzard never looked back into it... they changed that the damage cannot stack anymore ffs. I really hope one day they will undo the nerf. And yes it was the funnest spec to play =/