The bigger lesson is that there is rarely a single food that is universally “good” or “bad” for everyone.
Your individual health conditions, medications, allergies, kidney function, sodium and potassium requirements, and overall diet can all change what is appropriate for you.
If you have kidney disease, take warfarin, have a known food allergy or repeatedly experience symptoms after eating cucumbers, don't rely on social-media claims telling you to completely eliminate them. Instead, ask your doctor, pharmacist or registered dietitian about your specific situation.
Cucumbers may be perfectly healthy for one person and something that needs to be limited for another — and understanding the reason is much more useful than simply calling a food “good” or “bad.”