The usefulness of ignite

Is it supposed to be hard to get 5 stacks of poison? Regular poison has a duration of 2 seconds, so even a moderate attack speed of 4 hits per second can easily stack more than 5 even without increased duration. And obviously, if you go poison, you'll try to get as many stacks as possible. For example a Chaos Storm build can reach dozens of stacks.

I'm currently using burning arrow for a 100% ignite build with sudden ignition jewel to apply two stacks. I'm using Xoph's Nuture, The Signal Fire, Dyadian Dawn, anger, HoA,. With elemental overload, 4 frenzy as Trickster, Burning Arrow + Burning Damage + Chance to Ignite + Ele dmg with Attack + Immolate + GMP and given that the enemy is already burning, only 32k dps can be reach per stack and around 65k total dps from ignite. Clearing is fine, but boss is the problem. It is not a very good figure for an ignite build as I have no way but flammability to reduce enemy resist. This is also why I pick immolate over deadly aliment as my hit can do another 30k dps by doing so. It feels bad for every boss fight. I'm thinking should I use scorching ray totem to reduce boss fire resistance but I must drop decoy totem. Without decoy totem, boss fight will be much harder as we have limited leech as an ignite build.

As "Vipermagi" mention, as long as you can reduce enemy resistance, ignite build is fine. However, currently we need to invest a lot to really reach that resistance reduction. Burning arrow with Dyadian Dawn can do 40%*2*1.35 = 108% damage of base damage. But I wondering without the help from Sudden Ignition and Dyadian Dawn, can other ignite build reach a good dps.

More importantly, the two problems ignite build suffering need to be fixed in order to make ignite great again.

1. Fire resistance reduction. We can't truth curse as mods can be hexproof. However ignite can't enjoy anything from resistance penetration. Resistance overcapped enemies will be a great problem. Using a scorching ray can help a little bit but it can't solve anything. There should be some ways to "penetrate" enemy resistance for DoT damage.

2. How to get the life back. DoT build won't do a great hit, so relying on leech is impractical. With the new life flask pantheon, life flask gives a large help but it's still not enough. Life regen won't be enough as long as you are not using Chieftain. Maybe ES build is the solution but limiting a general build (ignite) to a class (Chieftain) or ES is not a good thing for build diversity. In fact this is not an issue of ignite build only. Trap and mine build also suffer. GGG needs to find some ways in passive (not unique) to let the player to get some life back. Otherwise, players will keep relying on VP and the situation "VP for every league and every build". Doubling life regen from passive and providing more life regen in the north part of the passive is an example (just double the self-burn from RF at the same time to solve the problem). Comparing to leech, 10% life regen is still not enough for hige-tier map, not to mention isn't really hard to get even 5% in the north part of passive if you are not Chieftain.

Another suggestion is that there can be a life leech for DoT from the north-east side of passive. To make it not too strong, leech from DoT and hit can't stack. Only the higher one will have the effect. Sure, it's still leech and it won't help trap/mine build, but it saves some DoT oriented build.

Edit: Decoy totem is a better option for tough boss personally.

It's pretty simple. There is only one way to build around ignite as primary source of damage. And that is Elemental Equilibrium + dual curse, and backup scorching ray(for curse immune or high hp boss). Don't try anything else, it won't work. Fire penetration doesn't work on ignite (even if you are gaining it from other sources that says "Damage penetrates fire resistance") All penetration is a property of hits therefore damage over time cannot penetrate.

When making a build you should always imagine the worse case scenario, since any build can effectively clear trash mobs. A 50-75% resist target will take very little damage with ignite and there is no other way other than EE to reduce. On top of this, ignite has very low scaling due to no more double dipping therefore as Vipermagi said, negative resistance stacking is the only way to really scale the damage even if the target has no resistances, but it still will not match a good poison build or other top tier builds, although I might be wrong about this.

Still, I really think that forcing people into resistance reduction as the only way to even make ignite viable is not good design, hopefully there will be changes in the future.