Why is sig spam unbeatable???!

Sig spam is broken, it's genuinely unfair. and before you say "if so good why no use in tournament" like an NPC, because those are the GREATEST PLAYERS OF ALL TIME!! Sig spam needs to ​​​​removed from the game. Literally goes like this: I wait for Sig, opponent does Sig, I read it and attack to punish,they dodge and have enough time to punish me with another Sig even though they should have way more recovery frames/endlag from such a massive attack. SSBU doesn't have a smash attack spam problem because it's actually balanced. How does ANYONE except for the top 8 players beat Sig spam???​​​​​​