I don’t see why you have to use it if you don’t want to. But you are expected in a raid setting to be mindful of mechanics. I have raided plenty of times with people who do not use any addons, and they do better than the folks with them. Some people find addon/DBM etc a distraction.
And for those guilds who refuse to invite without these addons, show them you can do the fights without it, the only concern is that pull timers are synched to these addons but that can easily be communicated.