That's really the major thing that made LAN parties so special. Being in the same room is so, so different than online gaming together and hanging out on discord.
It also forces you to compromise when choosing games and maps, because you're stuck together for the night. You can't just sit out a game/map if you don't like it, you can't just hop on a different voice channel and play another game with other people. You end up playing games you're not as familiar with (and not as dominant in), so your friends will play your game with you later. This brings you into situations, where the person next to you frantically gives you the crash course in rush build orders while building their own base, making the payoff so much better when it actually works out.