Another problem with the photo hosting sites is many people upload the photos at very high resolution, not a bad thing for people with big screens and unlimited very fast connections. However for those of us viewing on smaller note books or tablets having to reduce our browser to sometimes ~25% to view the photos in their entirety and then back to full size to read the text…
Not to mention when using a mobile connection the amount of data we are burning to view these massive photos. As has been mentioned there are many good options for reducing photos to web friendly sizes. Add to that the slow page loads.
If I know the only thing I’ll be using a photo for I often change the settings in my camera to save a much smaller image size.
The solution I used in the past when running Microsoft XP was the photo re-size that was part of their “Power Toys” really wish they would release a new version of power toys for Windows 10 or add a decent bulk photo re-size in one of their upgrade patches.
Any Microsoft employees listening?

Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.