pathfinder

why your conception of a warlock must be able to be confused with a wizard or sorcerer from an outside perspective

To me those three classes form a little triangle of being the "main" arcane spellcasting classes. Wizards cast through study. Sorcerers are just naturally magical. And warlocks get their spells through a patron. But all are general spellcasters, unlike, say, the nature flavour of a druid, religious flavour of a cleric, or the martial side of the magus.

The oracle is, in terms of its subclasses and feats, really good for this (with some reflavouring of the Mysteries to be applied to a specific individual patron, which is explicitly not what Mysteries are in the text). Its biggest problem mechanically is the core class using the divine spell list rather than arcane. And unfortunately that's a pretty big drawback to making the warlock fantasy work. But the bigger problem is the whole design of the Mysteries.

The fantasy of having a patron is not something that must be expressed mechanically

I just fundamentally disagree with this view. The patron of a warlock is critical to the warlock fantasy for me. It's like suggesting you could play a rogue fantasy by being a fighter with high dex and a finesse weapon. Like, yeah...you could. But having a proper class that more accurately represents the fantasy would be so much better.