The reason why tzara’at no longer exists is that it afflicted only people who had refined their behavior and had risen to extremely high levels of Divine consciousness; these levels of consciousness are available to us only when the Tabernacle – or its successor, the holy Temple – is standing.
Healing Subconscious Flaws
אָדָם כִּי יִהְיֶה בְעוֹר בְּשָׂרוֹ . . . וְהוּבָא אֶל אַהֲרֹן הַכֹּהֵן וגו': (ויקרא יג:ב)
[G‑d told Moses,] “If a person develops [certain kinds of lesions on the skin,] he must be brought to Aaron the priest [in order to determine if he is afflicted with tzara’at].” Leviticus 13:2

The first types of tzara’at that the Torah discusses are those that appear on a person’s skin. The skin is the external layer of our body; this type of tzara’at therefore alludes to an imperfection in our external behavior. Specifically, it afflicts people who are guilty of unintentional, spontaneous injurious gossip or slander.

We can indeed purify our deliberate behavior, speech, and thought of negativity. Nevertheless, some subconscious negativity might remain, lurking so deep within that we might never become aware of it on our own. When the only trace of negativity remaining within us is this delicate, the only way it can surface is in spontaneous behavior, such as unpremeditated gossip – the casual remark that slips through otherwise innocent conversation. Spontaneous speech discloses the inner recesses of the heart.

When the Tabernacle or Temple stood, G‑d let people know when they still possessed this slight imperfection of character by afflicting them with tzara’at. Although we lack this open sign today, we can still notice the slips of our tongue and take them as cues to refine ourselves accordingly.1