Understanding the trade-off.
WHAT THEY DO
Add functionality WordPress does not include: forms, shops, security, caching, backups, SEO tools.
WHAT THEY COST
Code loaded on every request Database queries Scripts and styles added to every page Maintenance and updates A potential security weakness
WHY THAT MATTERS
Plugins are the most common route of compromise on WordPress sites.
Not because plugins are bad, but because outdated ones have known vulnerabilities.
THE PRACTICAL POSITION
Every plugin must earn its place.
A site with forty plugins has a maintenance problem, a speed problem, and a larger attack surface.
THE QUESTION TO ASK
Does this solve a real problem, and is that worth the ongoing cost?
WHAT TO AVOID
Installing plugins to try them and never removing them Installing a plugin for something the theme or WordPress already does