By Comparison a condi user, invest in a single trait line and the condition dmg cannot be dodged, blocked or reduced, meanwhile the condi user can invest in tank stats without losing DPS
This is not true in the least. Abilities that apply conditions can be dodged in the same manner as abilities that inflict direct damage. You can avoid condition damage using the same mechanism. The same thing applies to abilities that are blocked.
In addition, you did not account for the fact that conditions can be cleansed. A 20 second burn can possibly kill you outright, but not if you cleanse it after two seconds. There is no comparable defence for direct damage in which can just remove potential incoming damage.
HoT will introduce the resistance boon, which will negate all conditions applied to a target. The only equivalent for power based damage would be a boon that negates all direct damage, which currently does not exist nor will exist. The only things comparable to this are abilities like endure pain, which are relatively short in duration and on a long cooldown.
In addition, traits do not generally include things like condition duration and condition damage on the same trait line. Furthermore, condition builds often need to opt for some precision in order to gain addition crit procs. So while there is no equivalent of crit damage for condition builds, they often cannot full min-max their stat choices via the trait system due to the way the attributes are spread out.
Lastly, condition damage users do lose DPS when investing in tank stats. For instance, carrion or sinister gear will provide higher DPS than dire gear, but the latter is tankier. Similarly, a burst damage build can maximize DPS by going, say, full berserker, but one can always slot in things like valkyrie, cavalier, or knight gear to help their survivability. Moreover, if you decide to go for things like apothecary gear, your condition damage is often so low that it’s often better to go for a direct damage build with cleric gear instead.
So while condition builds can be more effective some fights, this isn’t always true.