"Not using an IDE" can mean very different things depending on how you define "editor".
I would say that an editor that INTEGRATES knowledge of your source in some way, like auto-complete, or red-squiggles, is very much a big step towards an IDE and should could as "using an IDE". Whether it does that using plug-ins/extensions or natively doesn't matter. If it has that functionality there's not that much more separating it from an IDE.
VSCode, for example, is more like an IDE than an editor especially as you add more and more extensions.
I would say that an editor that INTEGRATES knowledge of your source in some way, like auto-complete, or red-squiggles, is very much a big step towards an IDE and should could as "using an IDE". Whether it does that using plug-ins/extensions or natively doesn't matter. If it has that functionality there's not that much more separating it from an IDE.
VSCode, for example, is more like an IDE than an editor especially as you add more and more extensions.