So when and how bitcoin wallets in mobiles and desktop is considered to be insecured too? The difference is only the latter needs installation.
There is a big jump from a website to a mobile and desktop wallets! When you open a website you have no idea what you are running and what you are sending to that website's servers and you have no way of knowing it. But with a desktop/mobile wallet you have a choice to download and install what is open source so you can verify that it is not doing something malicious.