I mean it would be realistic to gain permanent attack speed because of high strength and agility
All RPG combat simulation is an exercise in simplification. You could dedicate phone's entire CPU cycle to trying to simulate combat and not even get close to accuracy.
If we were to try realism, armoured entities would be nigh invulnerable to arrows and swords, a single hit from a giant or dragon sized creature would kill a humanoid and with ease, player characters would run in terror when entering an undead-filled dungeon, mobs would almost always overwhelm a player character, combat fatigue would be an issue, a warbow is literally useless in the hands of anyone other than an archer who has been practising multiple times a week since birth, and literally hundreds of other factors all interplaying.
As for multiple attacks per round, if the player gets them as they advance why not give them to more advanced opponents? Not that I necessarily agree that multiple combat-effective rounds per second is even realistic.