Disadvantages of Projectiles
Though quick in release, once projectiles are released you have no control over them. It's generally the same in every case with projectile based weaponry minus attachments like wire that allow you control. However in the case of chakra based projectiles like these, after exhaling exit from the point of release there is no real control over the projectiles. The direction you've launched is where it will go and it could be very easy to avoid them with basic techniques that could move you out of the line of fire, like Earth Release Technique or the popular hurricane fist into the air. There is the problem of the rapid fire projectiles. As said previously, as you're allowed to fire multiple shots from certain techniques, yet they don't all have the power of that particular rank, their collective power combined = the rank of the technique as a whole. What this means is, as you divide the projectiles into several shots, they considerably get weaker allowing for your opponent to exploit the weakness. Some techniques may converge at a single point (usually the target) so that they may not be able to avoid harm by just attacking individual shots, there is still that possibility. Those who try to cover a wider range with more projectiles will leave themselves at a disadvantage. The opponent can protect just their frontal or the area of where they're attacking by using weaker attacks protect against individually weaker fireballs or fire projectiles. Another big disadvantage is this method is that these techniques aren't ver prone to combos with other techniques, especially those of other elements. The projectiles are generally so compressed and dense that they explode on contact, preventing them from melting or heating earth that could be used in a combo with them. The sheer concept of a projectile makes it less prone to be comboed with wind or lightning as the projectiles would require insane precision to be comboed with a wind or lightning technique. Projectiles aren't also very usable with water for the same reason as earth as the projectiles would simply "rupture" and not deliver its effect due to the small time in contact with the combo technique. The main disadvantages are that projectiles are fast yes, but less versatile in combat and for the most part, easy to defend.