に限ったことではない【にかぎったことではない】

に限ったことではない means "it is not just X": a problem or a habit people associate with X is in fact wider than X. It follows a noun, and the topic – the problem itself – comes first with は.

Carrying on: に限ったことではなく

To go on and say where else it applies, end the first half in ではなく and name the wider case with も or でも.

Ending the first half in が instead concedes that the point is wider, then turns to the case at hand.

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に限ったことではない belongs to formal writing, news and speeches. にかぎった限ったはなし話ではない means the same and is a little more conversational; in everyday speech, say だけじゃない.