I have two DDs, the youngest is 11 months, not yet walking but into everything. I am seperated so a single parent to the both of them, they see their father at the weekend.
When DD2 was smaller, she loved the jumperoo and this was ideal for me to shower/get DD1 ready for school/cooking etc. but she is getting bored and cries.
I have babyproofed the front room but there are obviously still a few unavoidable dangers and because of the age gap between the two of them DD1 sometimes has inappropriate toys so I wouldn't feel comfortable leaving the room to say go to the loo.
I was looking at playpens, which I could then fill with her toys and she would be happy and safe for the times I need to leave her unattended.
I mentioned this to my DM who said "why do people need to cage their babies?!" I ignored her but mentioned to my ex and he said "like a baby jail?" 
It seems to be a no no. Why?! Seems a perfectly safe happy environment and will only be used when it needs to, I wont be plonking her in 'jail' to sit and read a book for goodness sake.