To answer the OP, yes size does matter. As people have said, if you are in the average range, you're going to be fine with the vast majority of women. There are some size queens for whom not having a huge cock will be a deal breaker, but these are a minority.
Unfortunately the societal phenomenon of women mocking small penises and generally just being quite cruel about this issue isn't going to change. In our highly polarized society, many people are looking for an angle on how to hurt others. Penis size is the most well known male fear and women know this, therefore the percentage of women with malice in their hearts are always going to attack male size insecurities because it works, as a form of sadism it is effective. It also allows them to "come together" in conversations and bond as women in a girl-bro kind of way. For many this kind of cruelty is seen as an empowering ownership of their sexuality, a "fuck you I'll say what I want", I know that this sucks but that is just the way society is at the moment.
If you are truly small, this will be a deal breaker for many women. And if you sleep with a chick, she will probably tell her friends you have a small dick. Some will be too embarassed to tell their friends, some may even lie, some may even lie out of empathy for you, but most won't.
I think the reason this topic is constantly relevant, despite the fact that these "it's not so bad bro" answers have been the accepted wisdom for 20 years, is because for most men who have size insecurities, the "it's not so bad, you're just fine, your girl might prefer a bigger cock but you may have other qualities that allow her to overlook it", doesn't really get to the core of the fear. The fear being that you're not hung and you lack something that many women lust over, and that is seen as virile and masculine. And while you can definitely get laid with a small dick, it's getting laid with an asterisk*, which is the brutal truth that if you are small and you want to be sexually active, people are going to find out that you are small. Her friends will probably find out, your social circle will probably find out and discuss it behind your back. And all the rage and shame that comes from this cruelty is something that you will have to face, and you have to come to terms with the getting laid with an asterisk* aspect to being a sexually active smaller guy.
The further you push game, the more seductive you become, it doesn't make this asterisk* go away. Because among the sexually active fashionable cool chicks who discuss everything in gory detail, they will say "oh he's that really cool guy, but I've heard he's got a small dick though. OMG really? He's small? I would expect him to be bigger lol". The more socially present and the more you engage with the world, the more you become a topic of discussion, the more this will become known. That's why smaller guys disappear and retreat from the world, why guys at group sex parties are generally above average, why guys into polyamory are above average, why successful players are above average in size. The smaller guys are too wounded to try. They've already been psychologically annhiliated by society, so they run away.
There's no amount of "it's cool bro" talk that's going to remove this brutality. We've all heard the stories about the small dick guy who owned it and came to terms with it, this is just a guy that faced this brutality. But he did have to face it, and he didn't face it by soft talking himself with sweet nothings and wishful thinking. He likely faced it with self forgiveness in times of extreme emotional brutality and cruelty, "castration" you could even say. Ultimately this is always going to be a question of whether you can accept the fact that you are small, will always be small, and that people may find out, and sadistically mock you for being small. Can you face this without becoming bitter? It's either this, or retreat from the world forever. Pre-emptively disquality yourself from life out of the fear of being emotionally castrated by women and society (like incels do). This topic always comes up because smaller guys naturally don't want to face something this difficult, and understandably so.