Minecraft by itself has an immersion problem, in that the player is easily able to access non-diegetic information. Particularly, this is the coordinates, light level, biome, and even the number of entities in the field of view, is the F3 debug menu. If you can see the seed, then that opens you up to using 3rd party tools for finding structures, slime chunks, and biomes. If you want to meet up with a friend on a server, align two portals, optimise a mob-farm, or just find your way back to your loot, you'd be silly not to use the F3 menu, and the game makes no attempt to stop you. Speedrunners even use the entity-count and FOV changes to pinpoint the tile entities at the End Portal, though speedrunners are hardly concerned with immersion. To me this feels like metagaming, and I believe this to be bad game design.
But just disabling the F3 menu's metagaming features with a mod like InGame Info XML leaves the player at a significant disadvantage, which isn't fun nor balanced. The compass and the respawn compass are insufficient for navigation. Maps work to an extent, but the player needs to acquire a lot of paper to craft a large one if playing in a version before functional cartography tables, and they're unsuitable for travelling more than 1000 blocks. Furthermore, there is no vanilla method for knowing light levels for mob spawning, or Y height for mob farm drops or just for building.
The solution is mods. OpenBlocks adds a luxmeter and a barometer. Navigation can be made trivial via minimap mods, though personally I see those as being too powerful and immersion-breaking. On the other side of things is the Antique Atlas, which only gives a rough overview of the terrain, but isn't limited by distance like vanilla maps are. There are also utilities in mods that allow for intuitive alignment of nether portals, though I do not remember which mod has this feature. Gravestone mods remove the stress in finding your items before they respawn, assuming they're compatible with items placed in accessory slots from other mods. There's even mods that will guide you back to where you died without needing F3, though that feels as cheaty as a minimap to me.
Now whether this matters to you depends on the type of modpack you're creating. Vanilla+ modpacks are more likely to care about immersion to some extent. High-difficulty modpacks may remove the F3 menu as a part of their difficulty curve, or they may keep it because you're going to need it to get back to your stuff again and again. High-immersion modpacks of course will care about removing F3 and likely replacing it with something as I detailed above. High-power tech or magic packs might not see any problem with the power presented by even minimaps compared to your mining laser or red matter armour.