While I guess it's all "each to your own" but I find alcohol in general to be less respectable/spiritual than psychedelics and it could take away from that aspect of a trip both in it's effects, and just the vibe I'd get from consuming alcohol while tripping, just sort of negative and "dirty". But I feel that way about any substances consumed while tripping other than smoking marijuana.
I went into my first LSD trip pretty beer drunk, and I'd say yeah it eased the come up, and I probably go as far to say that if the group of us hadn't been drunk, we probably wouldn't have made the unanimous decision to take acid that day hahaha. Oh, still probably one of the best days of my life