Why can't I buy XMR on Coinbase?

Could you please explain to me why I'm unable to purchase XMR on the Coinbase platform? I've been interested in adding Monero to my crypto portfolio, but I've noticed that it's not listed as an available asset on the exchange. Is there a specific reason behind this? Is it due to regulatory concerns, technical limitations, or perhaps something else? I'd appreciate it if you could clarify this matter for me. Additionally, could you suggest any alternative platforms or methods that I could use to acquire XMR? Thank you for your assistance.