> in article 5, Conveying Modified Source Versions, it only says that the work must do the following:
You have to keep reading the entire license...
Section 6 of v3 begins:
You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:
a) Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange.
<or several other functionally similar ways are options in the full text linked below>
How is that not needing to convey your source changes to those whom you distribute the object code?
It’s been there since v1:
Paragraph 3 of the v1 or v2 GPL is similar to section 6 of v3:
You may copy and distribute the Program (or a portion or derivative of
it, under Paragraph 2) in object code or executable form under the terms of
Paragraphs 1 and 2 above provided that you also do one of the following:
a) accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of
Paragraphs 1 and 2 above; or,
<do other things that have the same effect>
https://www.gnu.org/licenses/gpl-3.0.en.html
https://www.gnu.org/licenses/old-licenses/gpl-1.0.html