Your designer has been on Pinterest too much and wants to implement a parallax design in your sites and it must effects your site SEO ….
Here’s How to Convince Them to Stop For The Sake of SEO:
Loading Speed
Google likes the quick sites and is a ranking factor. Parallax sites are image-heavy and take ages to load.
Key Content
Traditionally you place your most important content above the fold but will parallax sites all content is on one page, so there is not fold; thus, important content is at the bottom of the page.
Pages Indexed
The whole site will be in the index as one page, so if you are targeting a highly competitive keyword,
then you may not have any organic visibility and will get nothing on the long tail. You could try and rank for multiple keywords through supporting keywords in the title tag, H2’s,
and diversifying your backlinks, but it isn’t easy. A site with many pages has a chance of ranking for various keywords.
Topics
If your site offers one thing, then it’s fine, but it’s likely you would have multiple topics, e.g., clutch bags, tote bags,
and the best way to target all these topics is to create a separate page for each and optimize through Meta tags and deep linking.
So, parallax sites should be avoided otherwise you will lose your SEO status.