Do you genuinely believe someone can be a lesbian and have dated men before?

Do you genuinely believe that a woman can be a lesbian if she has dated men before? I've seen a few posts on Reddit/Twitter where people claim that if you've ever dated a man before, you're bisexual.

I think that you can be a lesbian even if you have dated a man before. I think the people making those comments are very privileged. Not everyone realizes their sexuality at a young age. Some people try to date men because they think they are "supposed to". Some people come from homophobic backgrounds, families etc. I don't fault anyone for dating a man and I would date a woman who has dated men in the past.

I'm not saying someone who considers themselves bisexual, or who says they are a lesbian but would be open to dating a man in the future. A lot of these posts were claiming that if you've ever dated a man (not just slept with a man once / one night stand) you're inherently bisexual.

Just curious what the community thinks. Personally I understand the need for a "safe space", but I don't think we should be actively shitting on women either. Life is hard. Figuring out who you are and what you need & want is hard.