I'd venture to say that it has some major advantages over playing friendlies at locals, honestly. That shouldn't be understood as "I don't think playing locals are helpful", it should be taken as, "Some things are good about netplay over lan".
- Without traveling (and spending money), you can break away from the "regional meta"/local meta that many people get used to playing due to the frequency at which they play.
- You can record every single match (given that you have the equipment capable) and analyze yourself constantly. This helps with learning mus, learning exact spacing, and pointing out/fixing your habits.
- You get to practice mentality in an isolated environment. This is one that often gets overlooked from a lot of people who play netplay, and that is that you get to examine your mentality without any external pressure, only internalized pressure that you create, which in turn helps with the internalized pressure that you create in a tournament situation, although it is quite different due to not having a lot of distractions (which I understand is a big part of dealing with tournament nerves, but I'm specifically talking about working on your internal game in an exclusive environment, not necessarily working on the relationship between internal game vs the external distractions. For the latter, you need tournament experience). When you're in your natural space (your home), things that take you out of your element might affect you a little more. Things like gimmicky setups at ledge that interrupt your pressure, even getting shield grabbed because a ping spike made you miss an input takes you out of your flow and tests your mentality. If you can learn to stay grounded mentally regarding dolphin and netplay's inherent flaws, then you'll train yourself to become more resilient mentally. It's hard to take an L when you could blame it on lag or something. Netplay helps with mental flexibility, and as such, fortitude.
That isn't to say it's impossible to do the same thing in bracket or in friendlies, but netplay lets you see exactly what is coming from your relationship to the game, without social pressure, without supporting friends that you can john to, just you, the game, and a person out of touch with you.
(Also, people on netplay have mad grime,so that also helps with mentality lol)
- RPS game. If you can't rely on reactions as much, you have to learn to read them a little bit more, or at least position yourself for much easier reactions.
- Stage control. This one you can get from playing on a crt but on netplay, neutral is extremely outlined due to the inconsistency with punish game, and needing to react to missing a combo you would have hit on lan. This means you need to know where to position yourself in order to cover most options the easiest (obviously possible with lan as well, but because of the added focus of neutral game on netplay, you need to do it far more frequently). To be honest, punish isn't much different if the ping is stable. I think this is also where a popular opinion that slower characters benefit more from netplay comes from, because I think floaty characters and players often-times focus more on stage control, spacing, and habits than spacies do (especially on netplay because spacies players are often time focused on executing properly with the delay)
Obviously traveling and playing irl is the best way to get better, but netplay is really showing its colors for being the best improvement tool we have available currently, especially for people with not-as-good regions or people who simply can't make it out to every weekly/monthly.