Why does Rosa expect Rydia to be able to easily handle Black Magic?

[*Laurelindo*]

I refuse to be having fun. What do you think this is, kindergarden?

Of course it is, a Kindergarten full of Final Fantasy fun.

[Palom Porom]

Yuna was a high summoner,(FFX) and she wasn't skilled in black magic at all. Although you can put her in that direction lter in the game. But it does seem that in most FF's you are both skilled in Black Magic and Summoner.

[Mirage]

There's also no reason to think that the worlds of FF10 and FF4 are in any way similar.

[Palom Porom]

Yes, you are.

What is your theory on the hints from FF4 and FFT, then?
It definitely seems like Squaresoft were trying to imply that Summoners are essentially extra skilled Black Mages.

I only said that because this implies other FF games were also in the mix of this convo, even vaguely.

[SkyRender]

"
Rosa: Rydia, can you cast fire?
Rydia: No...
Rosa: Fire is the most elementary of black magic spells. As a summoner, you...[cough cough]
"
I guess Rosa is under the impression that a pre-requisite of summon magic is to be able to handle black magic. I'm too lazy to check all the messages in the mage hall/village of summons, but I'm sure it is understood that being able to summon monsters requires black magic.

[Ultima Spark]

From the Settings Guide:

When a Summoner learns summoning magic, it is necessary for her to master basic white and black magic - so Summoners can also use magic. (emphasis mine)

Summons are an advanced type of magic, of course it would make sense to start off with the basics.

[*Laurelindo*]

From the Settings Guide:

When a Summoner learns summoning magic, it is necessary for her to master basic white and black magic - so Summoners can also use magic. (emphasis mine)

Summons are an advanced type of magic, of course it would make sense to start off with the basics.

Depends on how you look at it - Summons can be considered "the art of summoning powerful beasts", which is quite different from ordinary magic;
you essentially call for aid and have entities handle magic for you.
But if the summoning itself requires some form of actual control over the entities' respective elements then of course it would be necessary to become proficient in certain black magic.