People can think what they like and say/do what they like but (a) that doesn't change the law and (b) they need to accept that there are consequences.
A watermark is very helpful to brand your photos so that others can recognize them as your work. The best method to watermark your images is using Photoshop. At first, it might not seem to be the very easy, it gives you the most flexibility and allows you to watermark your images exactly the way you want to and also once you create your own watermark using Photoshop, you can easily automate the process using your very own Photoshop action, and even batch watermark images.
If you want to, Lightroom can make you a watermark.
HTH