Except the subjunctive almost completely lost its initial semantic value of expressing the hypothetical or fictious in French, and in most cases has been replaced by the indicative. (Contrast with languages like Italian or Spanish that
did retain the subjunctive in these cases, and look at the (many) situations where the indicative is used in French and the subjunctive is used in Italian/Spanish). These days, the subjunctive is mainly used in clauses where an infinitive could be used (
pour qu'il ait/
pour avoir,
sans qu'il ait/
sans avoir, etc.) In that sense,
après qu'il ait, on top of feeling more "natural" due to the symmetry with
avant qu'il ait, isn't as outrageous an error as académiciens would have you believe, it simply follows this very handy rule of thumb.
Generally speaking, proper use of tenses and moods is overrated; it is inconsistent across Romance languages yet speakers of either have no difficulty making themselves understood, or learning others' systems. Many non-Romance languages dispense entirely with this system and yet their speakers don't encounter any difficulties expressing the same shades of meaning as they would in French.
Generally speaking, proper use of tenses and moods is overrated; it is inconsistent across Romance languages yet speakers of either have no difficulty making themselves understood, or learning others' systems. Many non-Romance languages dispense entirely with this system and yet their speakers don't encounter any difficulties expressing the same shades of meaning as they would in French.