Why aircraft did not eliminate cruiser scouting

Did the cruiser's scouting role disappear once aircraft became available?

No. Aircraft took over much long-range reconnaissance, but cruisers still served as durable forward pickets well ahead of the fleet.

Aircraft increasingly handled long-range reconnaissance, but they were not immediately reliable in every weather or operational circumstance. The answer distinguishes broad aerial searching from a cruiser stationed far ahead of the main force. Such a distant or forward picket could maintain contact, observe an approach, and operate beyond the force's ordinary support radius. Historical uses of the word scouting include both finding an enemy and holding an advanced position.