No direct or categorical and stringent proof of the dogma can be brought forward from Scripture.To say that there is "no direct or categorical and stringent proof" of the Immaculate Conception is not the same as saying that the Immaculate Conception "is not supported" in the Word.
To illustrate the difference, one could still find "support" for the dogma of the Trinity, even though "no direct or categorical and stringent proof" of the Trinity can be brought forward.
If it cannot be brought forward from the Word, that means it's not in there.
You will also note in that article there is not universal agreement among the ECFs on this issue either.
When viewed in totality the Immaculate Conception is not supported from a Scriptural perspective nor from the ECFs as a universal belief.
There is considerable support and evidence for the Trinity in the Word.