Taint is pejorative. Why must you choose negative terms to describe copyleft? Words matter, and words like "taint" and "viral" have been chosen for the purpose of harming copyleft's reputation.

I think I answered the asked question. By using the GPL the developer is choosing to have the rest of their application abide by the GPL, just like the LGPL or MIT/BSD licenses. The later examples require fewer changes, however, but in principle you're still abiding by the license.

I think a lot of modern tech companies are quite comfortable with the GPL. For the simple reasons that none of the restrictions affect them because they don't distribute binaries: their software all resides on servers (excluding the limited amount of javascript they serve to users).

The AGPL on the other hand, now that really is a hated licence: https://opensource.google.com/docs/using/agpl-policy/

>WARNING: Code licensed under the GNU Affero General Public License (AGPL) MAY NOT be used at Google.

>Using AGPL software requires that anything it links to must also be licensed under the AGPL. Even if you think you aren’t linking to anything important, it still presents a huge risk to Google because of how integrated much of our code is. The risks heavily outweigh the benefits.

>Do not attempt to check AGPL-licensed code into google3 or use it in a Google product in any way.

>Do not install AGPL-licensed programs on your workstation, Google-issued laptop, or Google-issued phone without explicit authorization from the Open Source Programs Office.

You are confusing companies that produce Open Source software (many of them are actually happy with the GPL) and those who want to consume Open Source, use it in closed products or services and give back little.