One AI Refused to Answer a Basic Marketing Question — And the Others Revealed a Fascinating Split on What Actually Drives Conversions

DeepSeek declined to answer a question about landing page optimization. Not because it couldn't — but because it claimed the topic "falls outside the scope of my designed functionality." For a question that every marketing team asks weekly, that's a striking data point about where different AI platforms draw their lines. But the more interesting story is in how the four engines that did respond diverged on which practices actually matter most.

The Comparison Table: What Each Engine Prioritized

Where They Agree: The Consensus Core

Four engines. Four different formats. One clear consensus: CTA clarity, mobile optimization, A/B testing, social proof, and page speed are non-negotiable. These five elements appeared in every substantive response without exception. If an AI were advising a junior marketer on where to start, all four would point them to the same place.

The agreement on form minimization is also notable — three of four engines flagged it explicitly, with Gemini even detailing form UX specifics like placeholder text behavior and single-column layouts. This reflects years of CRO data converging on a simple truth: every extra field is a conversion tax.

Where They Diverge: The Interesting Gaps

ChatGPT: The Post-Conversion Thinker

ChatGPT was the only engine to mention thank-you page optimization — "direct users to a thank you page that confirms the action and provides further instructions, which can also present additional offers." This is a genuinely underrated conversion lever that the others completely ignored. It's also the only response to treat SEO as a first-class landing page concern rather than a footnote.

Perplexity: The UX Behaviorist

Perplexity was alone in explicitly naming directional cues — "Use layout, arrows, color contrast, or imagery to guide attention toward the CTA." This is a well-documented conversion technique rooted in eye-tracking research, and its absence from the other three responses is a real omission. Perplexity also uniquely emphasized message match between ad and landing page, which is arguably the single highest-leverage variable in paid campaign optimization.

Gemini: The Strategist

Gemini went deepest on audience psychology, opening with a full section on "Understanding Your Audience and Goals