Is there an unneeded hostility towards regular classes in this game?

[Ryuko]

At first, I thought maybe you were a new player just starting out the game and that's why your SMN dps was so low... (214 was it?) There's no shame in not having the best gear yet. But now that I know you are i78... That's actually a pretty high iLevel! You should be doing AT LEAST 250 in most fights on SMN with your current gear... probably even more. When you get full i90, you should be doing around 300~ (with your pet added of course). I'm not going to ask you to post your rotation because a few people have already asked you to and you've refused. Instead, I'm going to offer this advice and you can either take it or leave it. Other summoners may criticize tiny things in my rotation, but trust me this will increase your DPS by a lot either way.

Start of the fight: tell Garuda to attack with obey. Never use Sic. If it is a fight with a lot of AoEs and dodging, be sure to place her so she doesn't take too much damage. Watch her HP and if it gets low, Sustain while you are dodging something of your own so little dps potential is wasted).
Greatest dps potential on single target (for burst moments, WITH all your cooldowns): RS > Bio II > Miasma > Bio > (wait for Bio to land) Fester > Miasma II (while triggering Contagion) > SC > Shadowflare > Ruin 2 (trigger rouse while waiting on GCD) > Ruin 2 > (trigger spur while waiting on GCD) > Fester > Energy Drain if you need the MP, or another Ruin 2 > RS is over... > Enkindle > Ruin 1 spam until refreshing dots... rinse, repeat.

When dealing with multiple mobs, make sure your 3 main dots are up with Bane, you are using Miasma II, and Shadowflare for the highest dps potential.

When dealing with multiple targets, there are a few questions to ask yourself:
How long do I expect these targets to be alive? (If they will be alive for a while, consider throwing Contagion on the mob you used your initial dots on before using Bane.)
How many targets are there? (If there are more than four total, your Bane will not hit them all. If there are considerably more than four, you may want to start by casting your dots on a mob on one side of the pack, Bane-ing, and then casting your dots on a mob on the other side of the pack, and Bane-ing. I do this on spiders in phase 1 of Turn 4, for example.)
Is it dangerous for me to go in the middle of the pack of mobs? (If not, Blizzard II should be your 'filler' while your dots are ticking and a lot of mobs alive. If it IS dangerous to go inside the pack, you can use Tri-Disaster instead (less damage, longer cast time, more mp than Blizzard II) or burst down targets that need to die fast with Fester...)

General rules...
Shadowflare is worth it if a single target monster will be in the area of effect for most of the spell's duration. If your party doesn't need you to save SC for possible raises, this is what I waste my SC on since it's a long cast time. Shadowflare is ALWAYS worth it on multiple mobs.
Miasma II isn't really worth it on single target unless you are extending dot duration with Contagion. Even then, some people are still kind of 'meh' about its potential. I personally like using it. Miasma II is ALWAYS worth it on multiple mobs.
Fester on cooldown unless you are saving your aethercharges for something specific.
Ruin II does the same damage as Ruin 1, except it is instant (distributes damage BEFORE the GCD is up) and has an added effect of blind. Generally, to conserve MP, don't use Ruin II all the time. Some good moments to use it are... while you are dodging something (to maximize dps potential), when something is ALMOST dead (and you want every second to count), and when you are trying to squeeze as much as you can into cooldowns (like RS and popping pet cooldowns at the same time). I also like Ruin II for in dungeons where I pull hate on adds and the mob is attacking me... because it blinds the mob.

You will perhaps be happy about this analogy...

Remember when you first did the arcanist storyline, and the NPCs made a big deal out of math and timing meaning everything to arcanist? That wasn't just corny roleplaying. It actually holds true with BOTH of those jobs. A summoner/scholar who knows what is coming in a fight will do a LOT better. Timing your aetherflow charges for juuuuuust the right moments is important. For scholar, it might be saving Lustrate for moments where the tank gets hit hard, or using sacred soil preemtively before a hard-hitting AoE. For summoner, it might be saving charges for adds you *know* are coming (Titan ex jails, or Ifrit ex nails)... But, the more you understand a fight, the better you will perform... you will be able to time everything perfectly, and this is what bridges the gap between arcanist and SMN/SCH.