Monoliths restrict growth.
When your presentation layer is tightly coupled to your commerce database (typical for CS-Cart, Magento, or older WooCommerce setups), scaling turns into a fight. Page speed drops under peak traffic, and even trivial UI changes require a full backend deployment.
Your marketing team ends up waiting on developers for every A/B test, and mobile conversion rates suffer because the platform simply can't render fast enough on the devices where most of your traffic now lives.