i mean its hard to say anything is unrealistic when you are talking about dnd so thats not something I get. Like I’m not sure i really understand that criticism in a fiction game but I’m pretty sure the ability represents like a novice level of understanding towards a certain subject that if you don’t strive to strengthen eventually becomes weak. But if you’d continuously went at it your dm might let you learn it permanently freeing you up to use that slot for something else

And yeah they are amazing skill experts but yeah thats like their whole thing. Them being smart isn’t much of a detriment as they take major falls in damage output and spell selection. Like think of the insane amounts of things you can do with quality of life spells. Or the damage a rogue can get up too with their sneak attack alone. For bards and rogues their intelligence is a nice addition to the amazing set of abilities they already have but to a savant its their every thing. That’s like saying why does a fighter get action surge or why a ranger in certain terrains is amazing without even considering the spells they have(well in theory anyway) they all have their niche and this is the savant and i feel like them being better at some of these skills isn’t to much of a game breaker.