If people liked what they saw, this steals thunder from the actual release. All it will do it set expectations higher, and some people will inevitably say “a leak showed the game was working 8 months ago - why is it taking so long to release?”

If people don’t like what they see it is an unfair judgment of the work and that’s disheartening

These people live under confidentiality agreements and don’t tell their friends or sometime even family anything about their work. Seeing some jackass leak everything invalidates all that effort and sacrifice.