In those days there was no notion of SPA or other contemporary well-established patterns for online interaction.

I authored several commercial sites using Shockwave and the like and it enabled us to give clients the ability to author media-rich and design-heavy presentations in a fashion they were familiar with from card decks applications. At the time doing so in a 'sexy' way made them stand out.

It was a cul de sac, but it was a worthwhile direction to test in terms of UX.

That it was proprietary was weighted differently in those days. The world was dominated by closed standards and open source was still vestigial especially in commercial applications.