How central is Dio to JoJo's Bizarre Adventure?

He's the organizing force of the franchise's first half. Part 1 is his origin story as much as Jonathan's. Part 3 is built around finally defeating him. His legacy — his bloodline (Giorno), his philosophy (Pucci), his Stand connection (The World / Star Platinum relationship) — shapes Parts 4-6 as well. You can't understand JoJo without understanding Dio.

What is Dio's meme legacy?

Enormous. "ZA WARUDO! TOKI WO TOMARE!" is one of anime's most recognized phrases in any language. "It was me, Dio!" (the "it was me all along" format) is a meme template applied across all contexts. "MUDA MUDA MUDA" (Dio's beatdown attack) is recognizable to people who've never seen the show.

Why did Dio specifically become a meme character?

The delivery. His declarations are operatic — maximum theatrical commitment delivered at full volume. The gap between the seriousness of the delivery and the content (time stop, beatdowns, road rollers) creates the exact incongruity that produces memes. He's playing a part that's two sizes too large with complete sincerity, which is irresistible.

What is Dio's influence on subsequent JoJo villains?

He established the template: philosophical coherence, dramatic power reveals, theatrical speech, genuine menace underlying the comedy. Every subsequent JoJo villain (Kira's obsession, Diavolo's paranoia, Pucci's religious devotion) has a Dio-shaped hole in their backstory — either connection to him or opposition to his legacy.

Why has JoJo's Bizarre Adventure survived and grown specifically because of Dio?

Because he gives the franchise stakes. Every Part introduces new heroes, new powers, new aesthetics. Dio (or his legacy) gives them something to measure against — the philosophical standard against which the Joestars' opposing philosophy is tested. He's the franchise's irreducible antagonist principle, which makes him necessary.