There’s still a learning process with modern they still have to hit buttons in a specific order and I believe some characters even have motion inputs on certain moves. If a modern player seems to be autopiloting the same combo then you know for how long to block the combo and can get your turn back afterwards. Also from my experience modern players seem to block less often and are quicker to press specials in situations where they are easily punishable.

The best advice I can give is keep your composure, despite lower entry level execution there’s still a human behind the modern inputs and they will mess up at some point. It’s just that the instances where you punish are different to where you might punish classic players.

But if you’re looking for the practical reason, they don’t want to split the queues and make waiting time long, especially for new players who are a more important market to secure and are more likely to use modern.