"Spamming"
This term is nothing new as far as fighters go. Despite what you think "spamming" is, it is usually described as doing the same move in repetition. For instance, doing Sub-Zero's slide multiple times back to back could be labeled as "spamming". Recently I've been noticing that "spamming" has had a negative connotation. As in, players are using it to describe someone's playstyle or strategy, in attempt to belittle their gameplay.
Spamming, whether it be a projectile, special move, combo string or whatever it may be, isn't necessarily a bad thing. A counter argument to that would be, "Well, what if they're being punished for 'spamming'". Even then, it's not necessarily something that you shouldn't be doing. Players "spam" for a shit ton of reasons, most in which are situational.
For instance, spamming a projectile accomplishes many things. It's good for zoning, creates space, it allows for space control, builds meter, does chip damage, etc. It's also good for mind games. Frustrating your opponent because he can't get in forces him to make mistakes. Mind games like this are something you have to be thinking about with every tactic in fighters. It can also be used to train your opponent. If you spam projectiles at full screen most of the time, or if you have a certain pattern with them, your opponent will adapt to that and try to counter them accordingly. Then you switch it up and don't spam projectiles at that same distance and dash in, or block and punish his counter you know is coming. Or you switch up the pattern, forcing them to jump in, then you anti-air them. All of this is accomplished by simply "spamming" a projectile.
The same things above can be accomplished with "spamming" other things as well. Such as I mentioned before, combo strings, other specials, hell even normals. Once you do something in repetition, you're training your opponent to look out for it. You may spam something 5 times in a row the first round, then never do it again. But your opponent will always be looking for you to use it, affecting his focus and his reads on you.
The main problem is, a lot of players see "spamming" as a scrubby tactic, or disrespectful, etc. There's plenty of reasons why it's viewed this way. One reason is because they can't beat someone spamming. Just because someone is doing the same thing over and over it doesn't mean it's necessarily easy to counter. So players use them spamming as an excuse as to why they lost, using the word spamming in a negative way to imply that it's the only reason they lost. It's also frustrating losing to someone spamming. It just doesn't look good losing to spam. But the thing is, it's not the spammers fault for why you lost, it's YOUR fault. Is it his fault that you don't know how to counter his spamming? When you have the mentality that spammers are bad players, you shift the blame off yourself. So you don't work at beating spam, you just view it as a scrubby way to win. This is true for a lot of tactics in fighters, not just spamming. If you want to improve, you need to take responsibility for your loses. You didn't lose because your opponent was doing this or that... you lost because your opponent was doing something you couldn't counter, or defeat. And despite what you may think, or what others have led you to believe, there's almost ALWAYS a way to counter a tactic such as spamming.
Every tactic is viable in regards to competitive gaming. As long as you're not cheating by going against tournament rules. Once you realize this, and that your opponent is always going to do whatever he can to win, is when you realize you need to practice against every tactic that is possible to use against you.