I'm sorry pemerton, the way in which you have quoted me here seems designed to not only hinder discussion, but misrepresent much of what was said. I don't even see how you could pull out the lines you did without reading the rest. Still;
How do we know they won't all rush in? How do we know that the gnolls will shoot arrows over the warriors?
They won't fit. We don't know that they will shoot their bows, but they should, or throw their spears. If the GM chooses to nerf them it is not a problem either for the system or the GM.
Maybe they're berserker gnolls. Maybe they've all sworn a blood-oath to Yeenoghu to tear the defiler limb-from-limb, and so the first thing they do is charge the cleric, with sneering disregard for his/her petty spirit guardians.
Sure, but nobody is saying that Gnolls shouldn't be played like that. People are saying that 5e Gnolls weren't designed to behave like that, and they are saying that if you play Gnolls like that you they will be much less of a threat. For example I said the same things here;
On one hand, this sounds like a cool picture, if that's what you are going for, but it doesn't make any sense for MM Gnolls. This is not playing the game RAW or RAI.
and here;
The example simply shows that playing monsters with terrible tactics and strategy, (aside from against their stats and any inherent motivations) leads to weird outcomes. Now, if the Gnolls were under some sort of spell or stricken by a disease, then several tons of Gnoll corpses in a small circle around the party could be a very cool image, but it doesn't make ANY sense for RAW and RAI Gnolls.
And in any event, Spirit Guardians doesn't seem to render the caster immobile. Maybe in [MENTION=12731]CapnZapp[/MENTION]'s scenario the cleric was using the spell as a mobile aura to cut down gnolls - that seems like a reasonable sort of tactic for an 8th level PC. It was other posters - eg [MENTION=6787650]Hemlock[/MENTION], [MENTION=6834463]happyhermit[/MENTION] - who seemed to assume that the shredding of 70 gnolls by the spell meant that the gnolls charged mindlessly into a stationary aura.
Actually, if you go back CapnZapp mentioned Gnolls getting hit by the aura twice without being able to attack, which means they charged into it (though there is still no way they shouldn't have been able to melee before getting hit the second time).
... And how do you know that they thought their brethren accomplished nothing - maybe dying in pursuit of a blood oath against the defiler cleric is the greatest glory a gnoll can accomplish?
Which again, isn't a problem. The problem comes in when one uses a situation like this as a "test" or an example of something, as though it is representative of what the game presents. It is only different in degree from saying; "I threw an archmage against the party, I took away his magic and gave him a stick and they shredded him. This is broken."
... And why will they almost always have "back row" options?
Serious question? Ok;
Because they can throw stuff.
Because they can use ranged weapons.
Because large groups cannot all get into melee.
Because in 5e the game, they almost always have them.
How do we know that Yeenoghu has not geased this group of gnolls to attack only with fang and claw, so that they can feel the enemy's flesh under their nails and taste the enemy's blood on their tongues?
Again? You ask the same question again? Nobody is saying the GM can't do this, they absolutely can modify the monsters in 5e it explicitly says so. It's just that if you do that it is no longer representative.
Strangely, some of the most on-topic points of my post you skipped such as;
...
In this scenario, how far would you have to nerf ranged attacks to make them less attractive than ineffectual suicide? Maybe if it was only 1 or 2 HP of damage, but even then there is a chance (or extreme likelihood) of disrupting the concentrating caster, or taking them down entirely. And if you nerfed it so hard that suicide was a better option than tossing rocks in this particular situation, then the Gnolls should simply run.
Frankly, the added details to the scenario raise more questions than answers, but CapnZapp doesn't seem to want to go into them so I won't pose more. I still don't know how this stuff worked;
Those who charged was slowed down by the spell's other effect, ensuring almost no gnoll survived to make melee attacks at all (since they need to survive two helpings of damage;