The IP address does not always tell you to which site you are connecting to. Many different sites can point to the same IP, more when services like Cloudflare are being used.
The extension is sent unencrypted, even when using TLS 1.3. So everyone sniffing the traffic can tell where you are surfing to, even without DNS.
There is little reason to support clients that do not support SNI. By supporting those clients you are likely putting your entire encrypted infrastructure at risk. SSL3 should be disabled by now. XP clients are legacy and should be taken out back and shot. Older mobile phones are enormous security risks.