This is easy: cost.
More features and extra services are add-ons that come with a price tag.
The core Shopify platform that many companies buy is $79 per month, with the most basic service starting at $29 and more advanced features running that number up to $299 per month.
For small online sellers, those relatively low costs are appealing. On Shopify Plus, merchants with anywhere from 0-$800,000 per month in sales will pay $2,000 per month and major online brands are paying up to $40,000 per month for their Shopify Plus platform. That’s a major difference, and it would be unwise make the investment in Shopify Plus before you have the sales volume to justify it.