From that support article:

> Last but not least, you need to comply with article 4.d of the LGPL license which has specific and very technical requirements. Complying with such requirements, which derive from the LGPL being used in the Arduino core, is usually a matter of providing end users with some documentation and binary files.

Article 4d of the LGPL requires library users to either:

> 0) Convey the Minimal Corresponding Source under the terms of this License, and the Corresponding Application Code in a form suitable for, and under terms that permit, the user to recombine or relink the Application with a modified version of the Linked Version to produce a modified Combined Work, in the manner specified by section 6 of the GNU GPL for conveying Corresponding Source.

> 1) Use a suitable shared library mechanism for linking with the Library. A suitable mechanism is one that (a) uses at run time a copy of the Library already present on the user's computer system, and (b) will operate properly with a modified version of the Library that is interface-compatible with the Linked Version.

Because the Arduino code is statically linked to your application to create the firmware binary, you're required to use option 0 (distribute your application's object files so it can be relinked with the Arduino library).

> And for some low-volume Arduino based products, the software isn't the valuable part of the project, anyway

That's definitely true! That's why I said I wouldn't use Arduino for a shipping product unless you're fine with the firmware on the device being publicly available.