"Spielzeug ist hingegen sinnvoll."

[Hohenems]

Should this not be "Spielzeuge sind hingegen sinnvoll" if the subject is "toys" and not "toy"?

[wataya]

Not necessarily. 'Spielzeug' can refer to a single toy and to a group of toys when they are viewed as a single group. If you want to stress the mess, 'Spielzeuge' does also work.

[Hohenems]

Thanks!

[amajou]

But why is "toy" wrong then? I guess you could make that sentence in English with "toy", or at least "the toy"

[wataya]

Without an article, the German 'Spielzeug' refers to more than one item.

[BigBob8989]

Can someone please explain how "ist" is plural?

[wataya]

please read the comments above.

[duoderSie]

think of it like "hair" in english. Hair can be one hair or a lot of hair but in both cases you use "is" not "are"