We were all into networking when I was young. Had to make Lan parties and UT servers work somehow.

Everyone still ended up working factory / distribution jobs lol.

Me too, but it didn’t really exist when I was 14.

He's probably using cloud services, makes sense, why build out infra he'll have to manage 365 when he basically needs it 2 months a year?

Aha, that's why I never get what I want for Christmas: classic ASP.

"there"

LAG are aggregated interfaces and they can indeed be used to prevent (some) layer 2 loops. LAG as in Link Aggregation Group)

Using 2 non-LAG interfaces between the same 2 devices creates a loop.
In the case of a loop, if you're running spanning tree, one of these interface will be blocking instead of forwarding, preventing the loop, but also percentile the use of this interface until the topology changes (ie: the current one goes down).
If you're not running spanning tree for some reason, then both interface will chug along, oblivious to the fact that there's a loop and broadcast packets will indeed keep being flooded on one and received on the other, again flooded, etc. creating a broadcast storm and impacting performance of the whole layer 2 domain and possibly even crashing devices.

A LAG more or less means the interfaces in the group behave as one big (aggregated) interface.
LAG also means you can push traffic on both interfaces for more bandwidth.

Source: ~~Network engineer~~ Internet plumber

It doesn't.

The assumption is that they're creating a high bandwidth trunk interface to the L3 switch/router, so if they forget to create an aggregate it'll be two independent interfaces and will down the network (or a port will auto down itself with STP, MSTP, etc. but that's not as funny)