It's okay to have an alt account, you just shouldn't create a new alt account for every new comment. This allows for their moderation systems to be effective.
My account is a great example. This account is separate from my real identity, and I use it to post about things I don't want associated with my real identity. I went through a period of poor-quality commenting that led to well-justified moderator action against it(I'm not exactly sure what, but I'm consistently brought to the bottom of threads). This is important for the site because it helps maintain a good signal-to-noise ratio and keep the site interesting and productive. If I were to always create a new account, it would bypass this important moderation tool. Reputation is important in any community, including this one.
My account is a great example. This account is separate from my real identity, and I use it to post about things I don't want associated with my real identity. I went through a period of poor-quality commenting that led to well-justified moderator action against it(I'm not exactly sure what, but I'm consistently brought to the bottom of threads). This is important for the site because it helps maintain a good signal-to-noise ratio and keep the site interesting and productive. If I were to always create a new account, it would bypass this important moderation tool. Reputation is important in any community, including this one.