Multiple A records is fine on root domain, but root can't use CNAME, which is used by some people to implement their dns load balancing (I use cname so I forgot that you can still do it using A records). By using root domain instead of www, your options for load balancing is diminished.

Edit: another common use case is hosting your static website on S3 or github pages. Typically it's done by adding a cname entry to s3 or github.io (been a while so hopefully I remember it right). You can't do this on root, unless you're using another server as reverse proxy (e.g. cloudflare's cname flattening service). Again, it's benefits cloud vendors (cloudflare got more potential customers by offering this service for free) but ultimately hurt people that want to host their small websites.