Indeed... well spitballed Genkaku.
All the necessities of Buddhism are internal to ourselves - namely the Four Noble Truths and the Noble Eightfold Path.
You do need some external... I mean, otherwise you wouldn't have the bathroom... but only the amount necessary to do what needs to be done. You don't need 84000 bathrooms, even if you've got teenage daughters.
"Having understood name-and-form, which is a product of prolificity,
And which is the root of all malady within and without,
He is released from bondage to the root of all maladies,
That Such-like-one is truly known as 'the one who has understood'." (Snp 3.6)
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)