The "training dummy" nonsense.

How would you react if you would hear something like in music you are just composing and executing alone, lol; in volleyball you have to actually beat the other team!

Despite the more than obvious stupidity behind this reasoning, it's one of the most common types of derogatory comments one reads in the context of DMC; and of course it's always from people who could not replicate combos like these (by Turtle Sensei) to save their lives even in a training room, let alone in a non-controlled environment:

Why is so important to have the option of a controlled environment and enemies in DMC?

When you learn to drive, you don't directly start in the middle of traffic. When you learn to play an instrument, you don't directly start playing with an experienced band. When you start with a FG, it's recommendable to first practice in a training room...

Such examples, however, only exemplify the most obvious (practice of fundamentals), and don't even address the complexity of DMC.

DMC's combat system is so complex in the proactive aspect, that players have developed a side-area like combo making, exclusively focused on the design and execution of combos in a controlled environment (with an isolated enemy) that would be virtually impossible to do in freestyle.

Such combos aren't only impossible because of the complexity of the interactivity of the move-set, boosted by tech; it's also because DMC is complex in terms of execution as well (5 being more lenient).

Being freestyle, combo making, speedrunning... After learning some fundamentals, there are advanced techs that are extremely hard to master, to the point that even after years of playing, many veteran players still can't do them consistently. A practice mode is still very useful after learning fundamentals, as there is still a lot to explore. From a tight set-up for a combo, to more complex variations for freestyle.

When you have such a complex system, the standards of performance come naturally from the range of players' limits and its distribution in a concrete moment:

A concrete player can bring up a certain level of creativity and keep a specific level of execution in a combo during X seconds. What he can do in freestyle will always tend to be less creative and less demanding in terms of execution, but much more improvised and with more enemies.

Apply this to all players interacting with each other and the product will be the current standards in freestyle and combo making.

Unless you are above or know for sure that there is someone/a certain group of players who are above the current standards without practicing with isolated enemies, individuals who can magically do harder/longer/more creative combos in freestyle than the hardest ones in the combo making scene, you don't have empiric evidence to support the idea that DMC doesn't need options to control enemies/environment.

It's true that many things can only be learned outside a practice mode in DMC, but without such empiric evidence, you just don't even have a basis to start counter-argumenting against a practice mode, let alone using the DMC is just beating a practice dummy lol type of retardation.

You aren't manlier either for resetting missions, isolating one enemy by killing or pushing away the rest in a certain mission or BP, etc.

Nobody with half a brain plays DMC because of how interesting and complex is to select options in menus to reset damn missions, and it's obviously nothing that takes any type of intellectual effort or dexterity.

It's simply annoying and time consuming.

The Void.

The Void in DMC5 is limited, but using this as argument to showcase how unnecessary or wrong are practice modes in DMC is as stupid as saying that a swimming pool isn't necessary to learn the fundamentals of scuba diving unless it can generate artificial waves of different height.

It still helps, and it's obviously the only option for console players to do proper combos without the hassle of resetting missions and isolating one damn enemy for every attempt. Combos having the same background (since it can't be changed without mods) doesn't mean that the actual designs aren't varied or optimized.

There is no logical base in such arguments, and you should be demanding a better void instead: with the option to change background, to choose the quantity of enemies, different types of platforms and/or spawning in certain areas like the Area Jump option of Super Trainer.

It would also be cool to have combo-mission types of exercises for newcomers, with ascending level of difficulty, like in FGs: