I'd be happy to. Imagine this. It's the second round of an online tournament. You're facing some noob. They use Pit and shoot arrows the whole match. Usually you'd be able to dodge, but this time the connection sucks. There're seconds of button lag. Frame lag makes the game look like you have items on and got a timer-clock. Even with this, you're able to get it down so you're both at one stock. He's at 150%. You prepare your ownage beam. Lag spike. You miss. But luckily you positioned yourself to follow with a dtilt. That'll KO him. You run to him and trip. He Fsmashes you. Round over, you lost. Now you lost to a noob, because of Brawl's online. Nothing more. Imagine those kids you 2-3 stocked all the time offline, who you nearly beat 3v1. That's who you lost to.
But at least you had a chance to play this time. Last tournament you kept waiting for your opponent to show up, took up precious time in your day just waiting by the computer. He said he'd be here sometime, never shows. The tournament organizer gets restless and flips a coin, you're out of the tournament.
And at least that person you lost to wasn't a whiny 10-year-old brat. Floundering to communicate in some non-intelligible language.
You decide to practice with someone else. Maybe give Wi-Fail another shot. It can't be all that bad. Some time has passed and you begin to forget the troubles past. But once again, you can't dodge a thing. You wonder why they installed the L and R buttons. Futhermore, this time your opponent seems to be able to avoid everything with ease. They have unlimited I-frames. You get hit by ROB's laser and top repeatedly. You go to take advantage of the recovery time that should be between his attacks, but he's still able to dodge somehow. You lose. Now your opponent thinks they're amazing. They love online play, feel it judges talent equal to offline. Is this really the community you want to deal with?
I haven't even gotten to the stages yet. Remember trying to recover on PS1 and getting consistantly caught under the lip and losing a stock and possibly a game because of that? That's relevant offline too though haha.
Well, that's all from me. If you do decide to get into competitive Brawl again, my advice is this: don't care about what other people think, just be yourself and play for yourself.