A "zero trust" approach where nothing is trusted and you pass through an SSO with MFA like Okta is better in that Okta do a better job in security than "random network team running an unpatched firewall from vendor X" do on average. And each service has an auth layer and doesn't implicitly trust some IPs are good.
In any case, a phishing that captures login+password+mfa means game over in both scenarios.